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  • Hello. I'm Margot Politis. Welcome to Study English, IELTS preparation.

  • Today we're going to look at conditional sentences. They're sentences that use 'if'.

  • If you listen carefully, you'll be able to hear Dr Malcolm Simons talking about junk

  • DNA, the parts of DNA that people used to think were just rubbish. Listen to the different

  • types of sentences he uses.

  • Under Darwinistic notions, you would think that junk would drop off under the theory

  • of natural selection, just like species drop off if they hit ecological niches, which is

  • incompatible with survival. If they can adapt to those niches, then those that can, survive,

  • and those that can't, die, is the notion. If you apply that to the DNA sequence, then

  • the coding region genes, which survive, have a function, and by the way the non-coding

  • sequences have survived as well. So the proposition would have to be that if they're there, they've

  • got a function.

  • In listening to Dr Simons, you can hear that he uses a variety of sentences. This makes

  • for much more interesting language. You should practice using sentences of different lengths

  • and types, especially complex sentences.

  • Today we're going to look at one of the ways you can create complex sentences using an

  • 'if clause'.

  • An 'if clause' is a phrase that gives a condition that's necessary for something else to happen.

  • They're often called conditional clauses.

  • If means when, provided that, or on condition that.

  • There are a few basic patterns for the 'if clause'.

  • Listen to this:

  • If they can adapt to those niches, then those that can, survive, and those that can't, die.

  • So the proposition would have to be that if they're there, they've got a function.

  • If they can adapt, then those that can survive.

  • The pattern here is: if + simple present tense verb, then ….

  • Then introduces a clause describing the consequences.

  • Look at the second example in the extract.

  • If they are there, they have got a function.

  • Notice that the then is left out in this example. Then is optional.

  • He could have said if they are there, then they have a function.

  • Let's look at some more.

  • If you have a university education, then you have more opportunities.

  • But the then is optional - you can leave it out.

  • If you have a university education, you have more opportunities.

  • Notice that this pattern can be reversed.

  • You have more opportunities if you have a university education.

  • We never include then when the pattern is reversed like this.

  • Let's try with the example from the story.

  • If they're there, they have a function.

  • They have got a function, if they're there.

  • OK, now here's the second pattern for 'if' sentences.

  • This is for when the suggestion is less definite, or less likely.

  • If you had a university education, then you would have more opportunities.

  • The pattern here is: if + past tense, then + would + verb.

  • If you had a university education, then you would have more opportunities.

  • We use this pattern when we are talking about the future, and about something that may not

  • be as likely to happen.

  • Compare these 2 patterns.

  • If you study hard, then you will pass your test.

  • If you studied hard, then you would pass your test.

  • In the first example, it's a bit like making a useful suggestion.

  • The second sentence is less definite, and less polite. It suggests that the person doesn't

  • study hard now.

  • So that's 2 ways of making the conditional tense - how to say that one thing will happen,

  • or might happen, if something else happens. There are other forms of the conditional tense

  • too.

  • If you learn them, then your English will improve!

  • OK, now we're going to look at ways of making opposites by using prefixes.

  • Listen to Dr Simons again.

  • Under Darwinistic notions, you would think that junk would drop off under the theory

  • of natural selection, just like species drop off if they hit ecological niches, which is

  • incompatible with survival. If they can adapt to those niches, then those that can, survive,

  • and those that can't, die, is the notion.

  • If you apply that to the DNA sequence, then the coding region genes, which survive, have

  • a function and by the way the non-coding sequences have survived as well.

  • In the passage we heard the words survive and die. They have opposite meanings.

  • 'To survive' means to keep on living and 'to die' means to stop living. We call words with

  • opposite meanings, opposites.

  • Sometimes opposites are formed from the same word stem using prefixes. Two of the prefixes

  • he uses are 'in' and 'non'.

  • Listen:

  • And by the way the non-coding sequences have survived as well.

  • He calls the junk DNA the non-coding sequences.

  • Non-coding means not coding. Notice that we use a hyphen with the non- prefix.

  • Non- usually forms adjectives.

  • It means 'not in the group of', so we have non-European, non-Aboriginal or non-government.

  • Non- can also just means not, giving a negative sense to a word - non-fiction, non-smoking

  • and non-stick.

  • The prefix 'in' is used with adjectives as well. It also makes opposites, and means 'not'.

  • It forms words like: insignificant, not significant; inexpensive, not expensive; intolerant, not

  • tolerant.

  • Another common opposite prefix is un-.

  • We can have unfair, unattractive, unusual, unnatural.

  • But un- can also be used with verbs. It means that an action is reversed.

  • So we have undo, undress or unbend.

  • There aren't many rules about what sorts of words take these prefixes. You'll have to

  • learn most opposites one by one.

  • A good way to do this is to try to find out the opposite every time you come across a

  • new word.

  • Finally for today, let's have a look at how you can form adjectives from people's names.

  • Under Darwinistic notions, you would think that junk would drop off under the theory

  • of natural selection.

  • He says under Darwinistic notions.

  • Darwinistic here is an adjective, but it's got a capital letter - do you know why?

  • Well, that's because It comes from the name 'Darwin' - referring to Charles Darwin, who

  • developed the theory of natural selection.

  • But it's got 2 suffixes: -ist and -ic.

  • The -ic suffix forms adjectives that mean belonging to, or like. So 'Darwinistic' means

  • like a Darwinist.

  • But a 'Darwinist'?

  • Well the suffix -ist forms adjectives too, but it forms an adjective that describes a

  • type of person with a certain set of beliefs.

  • When -ist is added to people's names, it means someone who follows that person, or who believes

  • in what they wrote or said.

  • So we can have a Darwinist, someone who believes in Darwin's theories, or a Marxist, someone

  • who follows the writings of Marx, or a Buddhist, someone who follows the teachings of the Buddha.

  • Well, we're out of time for today. Remember to watch out for those opposites, and try

  • using 'if' clauses.

  • See you next time. Bye Bye.

Hello. I'm Margot Politis. Welcome to Study English, IELTS preparation.

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B1 中級 澳洲腔

學習英語 - 第1系列,第14集:垃圾DNA。 (Study English - Series 1, Episode 14: Junk DNA)

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    大呆危 發佈於 2021 年 01 月 14 日
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