字幕列表 影片播放 列印英文字幕 - If the reserve parachute doesn't work the procedure is, basically you're gonna hand salute the world and you're gonna hit the dirt, 'cause you're gonna die. Hi this is Jocko Willink, and this is The Breakdown. [upbeat music] This is the movie "Navy SEALs". [dramatic music] - What's our altitude? - About 30,000, six miles up. - HALO jump is high altitude, low opening. You skydive through the radar, so they don't see you. You go at such a high altitude that they can't pick you up, and then you open your parachute at a low altitude, where the radar isn't effective. You'd be usin' this if you wanted to go somewhere and you didn't want anyone to know you were there. It allows you to get in without being detected. HALO jumping is fun. So if you're just training, you're gonna have a good time. If it's night, combat equipment, HALO jump, there's gonna be a little more intensity in a situation. But if it's just a fun free fall that you're doin' during the day for a good times, everyone will have a good attitude and be havin' fun with it. Let's go back. [tape rewinds] Loading magazines, that's pretty unrealistic. You should have your gear prepped prior to the jump procedures. - 45 minutes to the beach landing site. - That's one thing they usually miss in military movies, is in a helicopter, or an aircraft, it's so loud in there, you can't just be having a normal conversation. You gotta yell and scream at each other, or write stuff down, or use hand and arm signals. You know how much time, 30 seconds, means you're 30 seconds from goin' out. - What's a minute? - This right here. Super complex. - [Man] Six minutes. [dramatic music] - If you had a long flight, sure somebody might be readin' a book, why not. Almost every mission that I went on was in a vehicle. And in vehicle we weren't readin' books, because when you're in a vehicle outside the wire, then you have to be payin' attention for ambushes and what not. Outside the wire just means wherever you're stationed, you have a perimeter and the perimeter's got you know a wall around it, there's barbed wire on the wall. Barbed wire, so therefore we're inside the wire, and then the enemy is outside the wire. You know C130 is the actual transport plane that the military used for decades, and now we have newer planes. But I think this film is from 1990 and it's probably pretty accurate that a C130 would be used. The C in C130, designates it as a cargo plane. People think that it's bad flying in a cargo plane. It's actually awesome. And people string up hammocks and put down ground pads and get in sleepin' bags, and it's like time travel, 'cause you just go to sleep and you wake up and you're at your destination. I actually enjoyed travelin' in cargo planes, good times. Lemme fast forward a bit. [tape machine buzzes] When you jump out of an airplane, you're gonna have an altimeter, which is gonna tell ya what your altitude is. You're gonna have a parachute, and in this particular one, where they're jumping above 13,000 feet, you need oxygen, so they have oxygen on, which is just an oxygen mask. They're gonna depressurize the cabin, so they can open up and that way you're not breathin' that thin air. That's why they need to put those oxygen masks on. [dramatic music] - Jesus Dane, who the [beep] packed your chute? It doesn't look good, I wouldn't jump it if I were you. - What's happening right there is actually pretty realistic. Havin' your buddy check out your equipment. In the SEAL teams, and really in all branches of the military, you rely each other to make sure you're safe. The guy's checkin' the other person's pins on his rig to make sure that they're gonna deploy his parachute properly. And then he's actually messin' with him, which is pretty normal too. If you know someone's scared of parachuting then he's gonna get messed with a little bit more. Never let anyone know that you're scared of anything. Just keep it to yourself. Someone on a team's called a jump master. And that person is actually checkin' the navigation and checkin' the position, and making sure that we're exiting the aircraft at the right point. There's an actual school that you go to to become a jump master. And inside a platoon of 16 guys, there'd probably be two or three jump masters that could run a jump. - [Man] Three, two, one, [bell rings] go, go, go! - That's real, yep. The light system, where it's a red light, that means hold, and when that light turns green, that's the signal to go. [dramatic music] You gotta remember that that aircraft's movin' very fast. So if someone jumps and then you wait five seconds, you're gonna be too far separated. So yeah, you go out in a very tight group. You stay close for awhile. Once you get close to opening, then you separate a little bit, because obviously once your parachutes are open, you don't want people hittin' each other. So for a jump like this, you get to 2,500 feet and you're checkin' your altimeter the whole way down. You get a little separation from the other members of the team. This is your signal, it's called waving. So everyone knows that you're about to pull your parachute. And then you look in at your ripcord. When you pull your ripcord out, your parachute deploys. [dramatic music] So what you should feel when you pull your ripcord, is a little bit of a delay, and then something called the pilot chute, it's a spring-load small parachute, that thing jumps off your back and it grabs air, and then that's what pulls out the rest of your parachute. You're all of sudden pulled, it's like coming to abrupt stop in the air. So that's what it's supposed to feel like. But as you can see, in this particular situation, this guy isn't gonna feel a very hard shock, because he's having a malfunction. [dramatic music] - [Man] Oh [beep] - There's a buncha different things that can go wrong with a parachute. I had one malfunction in my career. See that, there's a little square there, right by his hands, above his hands. It's called the slider and it actually comes down. It's up with the parachute and as your parachute opens up it slides down towards the base. And sometimes that can get hung up. It's called a hung slider. And what it does is that small square of fabric keeps the whole parachute stuck together. That's what I had and my parachute was just not opening. What do you do when your parachute doesn't open? You follow the procedures. You know we train really hard to know what the procedures are. And there's some things that you could do, some procedures you can do, to try and get to clear that malfunction. So in my case, I was pullin' on the risers to see if I could get that slider loose, to start to come down. It wasn't working. I'm checking my altimeter, because at 1,900 feet, I said okay, this parachute isn't gonna work. And so then you go through your cutaway procedures. You arch to get your body position correct. You look at your cutaway, it's called a cutaway pillow. You grab it, you pull that, and then you look at your reserve handle, you grab it and you pull that. The first one cuts away your main parachute, so that it's not gonna interfere with anything. And there's actually a mechanism, that when you cutaway your main parachute, it starts to deploy your reserve parachute. So sometimes you don't even need to pull the ripcord. And hopefully you get a good solid chute at that point. Which, I'm sitting here today, which means my reserve parachute worked, thankfully. There's been guys that have survived, what's called a partial malfunction, meaning that they have some fabric up above them that's slowing them down a little bit. But if you're goin' terminal velocity and you hit the ocean, the ground, it doesn't really matter, you're dead. All right lemme play that. This is the partial malfunction. So you can see some of his parachute is open, now if you hit the ground with that type of parachute it's gonna be a real problem. You're gonna be severely injured. But if you hit the water with that kinda parachute, I mean you have a chance. - [Man] Get away ground. - So there's a cut away. - [Man] Pull out. - And there is his reserve, barely opens when he hits the water. He had a decent amount of cloth over his head. Once you hit the water, now you need to do a summary of your crew. And normally you'd be jumping out with a boat. I think in this particular scene, they commence immediately on a dive. Which is, which is not very realistic. The distance that you'd have to travel on a dive, if you were to parachute in, you'd have to be at least over the horizon, which is 12 nautical miles out to sea. You're not gonna be able to dive 12 nautical miles. There's no human diver that could do that. So that's pretty unrealistic. [upbeat music] This is "Act of Valor". - Black Bear it's Whiplash, have you loud and clear, 70 mile to set. - I think what they're tryin' to simulate here is something called a rigid hold inflatable boat. Which is a kind of common craft used in the SEAL teams. It's actually used for these type of situations that they're showin' right now in this movie, which is movin' up a river way, where you have a little bit more latitude to use a bigger craft. - Intended location is 15 Mikes. - 15 Mikes just stands for minutes. Mikes is minutes, it's kinda interchangeable. So the things on their helmet. This guy's got an actual light. I don't know why he's got it pointing backwards, but he's got a normal camping headlight. And then the other thing that they've got is a night-vision mount, but there's no night vision on their gear right now. Well we move underwater a lot, but we do it while we're diving. So appearing like that is not very realistic. One of the hardest things about maintaining a weapon is bringing it through the water, especially in the ocean. This is regular fresh water, so it's gonna be a little bit easier, but still, when you get outta the water, you have to make sure that the barrel is clear, and you have to drain the water outta the weapon. [dramatic music] [silenced rifle poufs] Just because you're in the SEAL teams does not mean that you are a sniper. Sniper is a specialized school that guys go to. And there's a buncha different schools. You could be a communications expert, you could be a medic, you could be a, what's called a breacher, where you work explosives to open doors. I was a communicator, so I went to a communications school. I went to a ton of other schools on top of that. But as far as major designations of school, I didn't go to sniper, and I wasn't a breacher either. [dramatic music] Freeze this frame. The reason you haven't seen a drone like this before is because in terms of drone technology, this is ancient. These were very difficult to fly. I mean nowadays they have little quad copter drones that a five year old could fly around if they wanted to. These were a lot harder to fly. You had to be a little bit more of a pilot to make 'em work. It didn't take very long for these types of drones to not be used by anyone. For just about any mission, you're gonna try and maintain security and silence for as long as you possibly can. And then the biggest thing you wanna get on the enemy is surprise. [dramatic music] [silenced rifle poufs] [dramatic music] Lemme pause it right here. This is just kinda not realistic at all. I guess they're tryin' to make things look cool. It always surprises me a little bit, because like I said it's the best job in the world. You don't really need to do anything to it to make it seem cool, it is cool. It's awesome. So as far as like a random dude being able to put is his hands up to time this sniper shot, it's dumb. [dramatic music] One of the things that makes being in the SEAL teams difficult is a lot of it is based around the water. If you're gonna be wet all day, guess what else you're gonna be? You're gonna be cold. And if you're in a cold environment, goin' in and being wet is definitely somethin' that's gonna affect you. We actually do use dry suits that keep us dry as we go across. A wet suit lets water in and it creates a very small layer of water between you and the ocean that actually stays warm. A dry suit keeps you warm by keepin' the water completely out, and you wear warmer clothes underneath it. But then you have a problem of dealing with a dry suit. I think one of the things that makes the SEALs good is we have to deal with that water element all the time. And so when we got out and perform missions where there's no water involved, it always feels a lot easier. [dramatic music] Freeze this frame. When you go to sniper school, you actually build your own, that's called a ghillie suit, what they're wearing. And when you go to sniper school, you actually build your own ghillie suit. There's parts of it that you can buy, but essentially they build those ghillie suits themselves. And they will adapt that ghillie suit for different environments. So if they're in a jungle environment they'll make it more green, if they're in a desert environment they'll make it more sand colored. And just depending on what environment you're in, you'll adapt your ghillie suit to match that. [dramatic music] The tap on the shoulder right there, it just means hey, I'm the last guy, and when I tap you on the shoulder, that means you can leave that security position. The problem with the hallway is there's a lot of unknown space ahead of you. Behind every one of those doors could be a threat. So what you have to do, is you have maintain that security. If somebody just throws a hand grenade down that hallway it's gonna be a problem. If somebody sticks a weapon around one of those doors and starts shooting, it's gonna be a problem. So hallways are definitely not somewhere where we like to hang out. The person that's lookin' forward has to maintain that front security. The person that's behind him, or maybe two people back is actually controlling the flow of the rest of the guys. [guns blast] - I got two squares comin' out the back door. - Everyone's wearin' a radio. Certainly they'll utilize the radios if you're outta line of sight of someone else. Also you just use verbal commands. I mean once the shooting has started, we're not surprising anyone, so we'll talk to each other, especially people that are in the vicinity, rather than having 30 people in the element, all talkin' on their radio tryin' to explain things, it's better to have the groups that are isolated together, communicate just verbally. If you have to communicate with someone that you're not within line of sight, then you can get on the radio. [helicopter whirs] This is "American Sniper". [helicopter whirs] - [Man] You said HUI has a sniper in the Olympics, but Iraq hasn't qualified a shooter in three games. - The film is actually about Chris Kyle. When I was a Task Unit Commander, Chris Kyle was in Task Unit Bruiser, that was my task unit. When the film came out, they actually had a screening for us down in Coronado at SEAL Team Three. That's when I saw the movie. A task unit is two SEAL platoons combined together. Then with a small headquarters element over it. That's what a task unit is. - Well that's 'cause Mustafa's not Iraqi. - In this particular case what they're tryin' to show is that the sniper's not gonna be alone. He's gonna have some kinda security with him. 'Cause if you're alone and you're looking down your sniper rifle then no one's covering your back. In this they're showin' Chris with one other guy. The reality of the situation in Ramadi, which is where Chris was with me, it wasn't just two guys, or three guys. Most of the time it was seven, eight, 10, 15, 20 guys, to maintain a sniper position. Two things that are kinda diametrically opposed that are goin' on when you're in a situation like this. They all want some kinda protection, which is why they're staying close to wall, which is, that makes sense. However, if you get too bunched up and a roadside bomb, or an IED goes off, a booby trap goes off, obviously the closer you are together the more people it's gonna wound. Hey there's times when you get bunched up, and you might be with two or three people to hold down a corner, but any military individual that's watching that, is not gonna get a good feeling seein' everyone bunched up like that. - [Man] Fire in the hole. [explosives bang] - I mean you couldn't see much of the breach, but essentially what a breach is, you put a big explosive breaching charge, which are specially made charges, that blow doors open. You take a step back and blow the charge. Yeah I mean that's pretty normal. There's advantages to breaching as well. So when you detonate a explosive breaching charge that's gonna stun the people in the room too. So there's some advantages, but there's also times where you wanna maintain, you know, silence. So there's advantages and disadvantages to both. - Hey, you all mind if I roll with you? - Hey man, any SEAL's cool by me. - When we were in the Battle of Ramadi, every operation we went out on we had Army, Navy, Air Force, Marines, with us all the time. I think this is representing a Marine Corps element. - You're the one they're calling The Legend. You got like 24 confirmed kills. - Well lose count. - If the situation's gonna call for him to have like a really long reach, being able to shoot very long distances, he probably gonna carry a specialized long distance sniper weapon. In an urban environment like this, be pretty common just to carry one weapon, that you can use a little bit in both environments. - Hey what does that mean? - Breacher up. - Tappin' your helmet like that, which actually the shooting hand came off, Chris would not take his hand off his trigger and be ready to shoot. This right here is breacher up. I talked about breachers earlier. That means this door's locked, or the decision's been made to use some kinda explosive breaching charge here. [door bangs] - Moving. - Get down, get down on the ground right now. Get your-- - Lemme break this down a little bit. What's difficult about fighting in a city is you have civilians that are running around intermixed with the enemy that you're fighting. One thing we have to remember about the Battle of Fallujah is there was very strong warnings to everyone that was civilians, to get outta the city. And the people that stayed there were considered hostile. - Get down, why are you here? You're supposed to be evacuate this area. Why are you still here? - If you've been told that everyone in the city is gonna be hostile, then they're probably takin' the right approach. Showin' Chris, sittin' there holdin' his weapon on this little kid, Chris wouldn't waste his time with that. He would move onto this adult immediately. What you're tryin' to do is get control. That's what you're tryin' to do. You don't know what's happened. When you walk into a room you don't know what's happening. Things aren't as they seem. So what you're tryin' to do when you get into a room is you're tryin' to get control of the room. I actually just mean, get control of the human beings that are in there. That could mean tellin' them to get down on the ground and they're not moving anymore. Cool, you have control. Now you need to actually make sure that they don't have any weapons. Make they're not rigged with a suicide vest, or somethin' like that, so that they can't attack you. Clearin' houses, what you're doin' is tryin' to make sure there's no bad guys in there. If they're in the streets you could take 'em out. But they're gonna go into buildings, they're gonna go into houses. It's the civilian populace that really suffers. In Ramadi where I was, the civilians were the ones that were suffering the worst because they were catchin' it from both sides. We would have Iraqi soldiers with us, or interpreters that would talk to the family, and sometimes you'd sense some uncomfortable situation, and then all of sudden you realize there was a person in that house that wasn't from that family. Well guess what? They were an insurgent, they were a foreign fighter, and we could catch 'em and take 'em out. [upbeat music] This is "Lone Survivor". - Way I see it we got three options. One we let him go, hike up, probably be found in less than an hour. Two we tie him up, hike out, roll the dice. He'll probably be eaten by [beep] wolves, or freeze to death. - Three? - Terminate the compromise. - You know in the SEAL teams most of the time everyone has the same general idea of what we should do, unless something is just grievously a bad call. Then someone might say, hey boss, that's not a good call right now. But yeah, for someone in a small group like this, they just talk too much. This is not rare at all for a group of SEALs to kinda discuss how we're gonna do somethin'. Now ultimately, that decision rides on the commander. And whoever's in charge of that element is the one that's gonna say, hey this was my decision and this is what we did. You can't as leader, once you make a decision, or once consensus comes in, and then things go wrong, you don't say, whoa you know that's what everyone wanted to do. You don't do that. You're the one with the final decision-making power. You can get consensus, you can take suggestions from other people, but ultimately when you're the leader you're in charge, and you'll own that decision that you make. - We let him go, 20 more will die next week. - Rules of engagement says we cannot touch them. - I understand. And I don't care. I care about you. I care about you. I care about you. I care about you. - Yeah you get a very specific rules of engagement brief, you know what the rules are. They could be as specific as you're not allowed to cuff females, or you're not allowed to enter a mosque, or you're not allowed to go past a certain line on a map. There's gonna be parameters that you're allowed to operate within. The big difference is in the SEAL teams the briefing is done by the members of the platoon and everyone kind of briefs their section. So for instance, the point man will get up and explain the route that we're gonna take to get to the target area. So that's all done by that point man. Let's say the breach team is gonna go in and do a breach on a wall, or on a gate, the breach leader will take over that parta the briefing and say, okay, once we get here, Bill you're gonna be there, Joe you're gonna be here, breacher's gonna come up, set the charge, then we're gonna take cover back here. So everyone kinda individually briefs their portion of the mission, so it's a collaborative effort. The briefs, we try to keep the briefs to an hour. You know after an hour, there shouldn't be so much information that it takes more than that. And after an hour, guy's hard drives are full. We want them to know the important things and we want them to understand the flow of the mission, and then once they have that, that's it. It is a big deal to break the rules of engagement, but at the same time, rules of engagement are written in such a way that if you think you need to do something, to protect your troops, or the mission, then you can pretty much do what you need to do to make that happen. And so this is a tough decision to make. They wanna execute this mission. They know they're goin' after a bad guy that's killed Americans, and at the same time, they got some people that they're suspect of, but they can't confirm, so it's a very tough decision to make. [upbeat music] This is Captain Phillips. [dramatic music] [men yelling in a foreign language] - In this particular situation, it's a maritime environment, it's on boats, and SEALs are the Maritime component of U.S. Special Operations. So if there's a strictly water operation like this, it's most likely gonna be SEALs that are gonna be executing that operation. - Sir the pirates have just issued a threat. - [SEAL Commander] What's the translation? - [Radio Operator] If he moves again shoot him. - That looks like it's just the control room on a Navy ship. That's what it looks like. There's a buncha screens there. There's a lotta communications going on in there. There might be 10 or 15 people that are in there observing what's going on, and communicating with each other. That's one of the things that we do all the time when we're training is we shoot what we call hostage scenarios. So they'll put a friendly target in front of a non-friendly target and we'll have to go in and shoot the bad guy, without shootin' the good guy. My task unit conducted one hostage rescue, during our deployment to Ramadi, where we went in, rescued a 15, or 16-year-old kid, that had been kidnapped by insurgents and was bein' held for ransom. Rescued that kid and it was successful. Somethin' that we train for. It doesn't happen very often. Hostage rescues are very challenging situations, because if you know a building's filled with bad guys, well then you can be very liberal in how you employ your weapon systems. If you're goin' against a target where you know there's friendlies there, like a hostage, then you have to be much more discriminatory in how you engage the enemy. - [Man] Alpha Charlie Red, we are cool red at this time. - Lifeboat, this is the negotiator, if you harm the hostage we do not have a deal. - I've never heard of a negotiation goin' down in a military scenario, because we're assuming that the people that have the hostages are hostile. And what they need to do is die. You know the SEALs that conducted this operation are some of the best guys in the entire world, and when they're gonna take a shot, they're gonna be ready to take that shot, and I don't know about this coordination system, if they used it awesome, but if they didn't it wouldn't matter, these guys are gonna get the job done. - Stop the tow. - Roger stop the tow. [dramatic music] - Execute. [gun blasts] - Generally, decentralized command is what we're dealin' with. So in that case, where the snipers are co-located like that, they'd probably be just communicating amongst themselves. You want your subordinate teams, when they launch, you want them to have the green light to go when things are ready. So that's a little bit micro managed, but I don't know how it unfolded exactly for real. We do know one thing, they rescued that guy and killed the bad guys, so credit. A lotta my vocabulary is infected, 'cause I was in SEAL teams my whole adult life. I mean occasionally I'll get funny look if I say check for instance. That's one where, if you tell me something, I might say back to you check. That means I understand, and I'm good with what you're sayin'. No factor, which is, you tell me that something is going on and I might look at you and say, no factor, which means I got this. Those are good ones because they're used a lot. I mean you can use them in everyday life. You know if someone says, oh no, there's traffic on the highway. No factor, I'll take the side roads. Like just normal stuff like that. But yeah there's a ton of things that we say in the military, it's just the way it is. You go into any organization they're gonna have their own little words that they use. That's just the way I talk now. [upbeat music] This is "Zero Dark Thirty". [helicopter whirs] - Helicopters are definitely one of the most common modes of transportation, but again, it varies from place to place. When I was in the Battle of Ramadi, the couple times that they did fly over the city when we were there, they got shot at heavily. Even to extract a wounded guy, we'd have to get him outta the city into one of the secure bases to get someone in a helicopter. Even for fire support, you know, in the Battle of Ramadi, fire support was almost all tanks and tankers. So God bless those guys for what they did. But in a situation like this, they're travelin' long distances, in Afghanistan, they used helicopters all the time. [dramatic music] Dogs are pretty common. Their senses that they have, what they can do. To be blunt about it, you can put them in situations where you wouldn't wanna risk the life of a human being. They use them for sniffing for explosives as well. They're great assets to have. Yeah looks like they're just naming what those helicopters are called and that's normal. Different aircraft will have different call signs. In this case, they're Prince52 and Prince51. I think what they're tryin' to represent is different phase lines of an operation. So in other words, as you move in towards a target, you'll have different marks. When you get past those marks, you'll call them up the chain of command, so everyone knows, hey we're at phase line Alpha, phase line Bravo, so everyone's kind of aware of where the mission is as it takes place. - Hey Justin, what are you listenin' to? - Tony Robbins. - Tony Robbins, really? - You should listen to him. I got plans for after this. - Looks like he's got some noise canceling headsets over his iPhone. So he'd probably be able to pull it off, crank up the volume. [dramatic music] That's just the border between Afghanistan and Pakistan. Guaranteed to have a phase line at that border. - [Man] We just crossed the border, now entering Pakistan. - Pakistani comms, no chatter. - Even though they've crossed into Pakistani land they're not hearing any communication from anyone. So they're sayin', hey look, we've gone into Pakistan, but no one's talkin' about it, which is a positive sign. [helicopter engine rumbles] They're night vision it looks like in all of these. Sometimes there's some more advanced goggles that have thermal as well, but from what I can see in these pictures, it just looks like regular night vision. Yeah some of those are just even more advanced night vision goggles that give you a better field of view. Yeah people get adapted to them. It takes you know, a couple hours of walkin' around, then you're adapted to 'em. If you come into a bright room and it bleeds out your night vision, raise your head a little bit and you can look underneath your night vision. It's not that big of a deal. Or you can just flip 'em up. You go into a dark room, you can just kinda knock your head forward a little bit, and those night vision will slip back down. So everyone finds their own little techniques on how they're gonna do it. - 30 seconds. [helicopter roars] - Yeah, basically there's a big thick rope, grab hold a that rope and you slide down like a fireman goin' down a fireman's pole. Pretty straightforward. - Stay tight. - Stay close so when the bird sets down and takes off, you want your group to be assembled pretty closely, until you start to move towards the target. I'd say one of the big misconceptions that people have of people that are in the SEAL teams is that they're some kinda super human individuals. You gotta remember that SEALs are just people and they train really hard, work really hard, to try and be good at our jobs, but they're still people, and they're not just Terminator robots. We watched a buncha movies of these different operations, or these fictitious operations, but we gotta remember that the SEALs, just like every other branch of the service has taken massive casualties, not only in our history, but in these recent wars. So even though it might look cool, you gotta remember that there's been real sacrifices made, not just by the SEALs themselves, not just by the Marines, and the Army, and the Air Force, but the families that are at home as well, that suffer those losses and live with those for the rest of their lives. We always have to remember what the real sacrifices are. That was my Breakdown, thanks for watching. [upbeat music]
B1 中級 美國腔 前海豹部隊Jocko Willink解密電影作戰場景|GQ(Navy SEAL Jocko Willink Breaks Down Combat Scenes From Movies | GQ) 38 2 紅紅 發佈於 2022 年 05 月 19 日 更多分享 分享 收藏 回報 影片單字