I
verb
1
BAD : Whenever I doubt about the meaning of a word, I look in my dictionary.
GOOD : Whenever I am in doubt about the meaning of a word, I look in my dictionary.
BAD : If ever you have any kind of doubt, come and see me or one of the other teachers.
GOOD : If ever you are in any doubt about anything, come and see me or one of the other teachers.
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(be) in doubt about sth (= feel unsure): 'Is anyone in doubt about what they're supposed to be doing?' 'If you're in any doubt about your child's safety, talk to your doctor.'
Note that this meaning is more commonly expressed by be unsure/uncertain (or not be sure/certain ): 'Whenever I'm not sure about the meaning of a word, I look in my dictionary.'
2
BAD : That is why we still doubt about beings existing in outer space.
GOOD : That is why we still have doubts about beings existing in outer space.
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have (your) doubts about ( doing ) sth = feel unsure whether something is true or the right thing to do: 'We have our doubts about sending Kevin to a boarding school.' 'Any doubts she'd had about marrying him soon disappeared.'
3
DUBIOUS : I doubt that she is telling the truth.
GOOD : I doubt whether she is telling the truth.
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When doubt is used to express certainty or near certainty, it is usually followed by a that -clause: 'There's no doubt that he's innocent.' 'I've no doubt that he's innocent.' 'I'm in little doubt that he's innocent.' 'I don't doubt that he's innocent.' In this meaning, doubt is used with a negative word, e.g. not/no/little/not much.
When doubt means 'think that something is unlikely', it is usually followed by if/whether : 'I doubt whether he's innocent.' (= I think that he is probably guilty) 'She doubts whether she'll be able to come on Sunday.'
Note that some people may also say 'I doubt that he's innocent', but careful users regard this as incorrect.
II
noun
1
DUBIOUS : There is no doubt that she doesn't want the job.
GOOD : She obviously doesn't want the job.
DUBIOUS : There is no doubt that most parents are willing to spend a lot of money on their child's education.
GOOD : Most parents are willing to spend a lot of money on their child's education.
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There is no doubt that is usually used in formal styles when you want to persuade someone that what you are saying is true: 'There is no doubt that the present government has lost a great deal of support.'
This phrase is sometimes used when a 'lighter' expression (e.g. of course, obviously, clearly, certainly, needless to say ) or nothing at all would be more natural.
2
BAD : It is no doubt that the rich have a great advantage.
GOOD : There is no doubt that the rich have a great advantage.
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there is no doubt that (NOT it is ... ): 'There is no doubt that the number of casualties would have escalated had it not been for UN intervention.'
3
BAD : Without doubt you're tired after your journey.
GOOD : No doubt you're tired after your journey.
BAD : The recovery of the Mary Rose is, no doubt, a great scientific achievement.
GOOD : The recovery of the Mary Rose is, without doubt, a great scientific achievement.
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without doubt = 'I firmly believe this to be true': 'He is without doubt one of the greatest composers the world has ever known.'
no doubt = 'I expect' or 'I suppose': 'No doubt you could do with a drink.' 'They will no doubt be writing to us again.'
4
BAD : Another reason for getting married is without doubt to have children.
GOOD : Another reason for getting married of course is to have children.
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Use without doubt with opinions and judgements: 'She is without doubt one of the kindest women you'll ever meet.'
When you mention a fact or something that is generally agreed, use of course : 'Mrs Thatcher is no longer in charge, of course.'