adv.副詞毫無疑問No doubt, he will succeed if he works hard.
phr.片語毫無疑問No doubt, he is the best candidate for the job.
phr.片語沒有疑問There is no doubt that he will succeed.
phr.片語無庸置疑No doubt you're tired after such a long journey.
n. (c./u.)名詞 (可數/不可數)懷疑There is no doubt in my mind that he is the right person for the job.