I
adverb
1
BAD : You better make sure you're not late again.
GOOD : You'd better make sure you're not late again.
BAD : My friends warned me that I should better be careful.
GOOD : My friends warned me that I had better be careful.
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had better (not) : 'If the phone rings again, you'd better answer it.' 'If it's a secret, you'd better not tell me.'
Note that had is usually shortened to d and sometimes may not be heard at all.
2
BAD : 'You'd better to hurry up,' she shouted.
GOOD : 'You'd better hurry up,' she shouted.
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had better (not) do sth (NOT to do ): 'You'd better not leave all that money on the table.'
3
BAD : Instead of using a dictionary all the time, you had better try to guess the meaning of the words.
GOOD : Instead of using a dictionary all the time, you should try to guess the meanings of the words.
BAD : If people want to be healthy, they had better be more careful about what they eat.
GOOD : If people want to be healthy, they should be more careful about what they eat.
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Had better is used in informal styles when you give someone strong advice about what to do in a particular situation. The situation usually exists at the moment of speaking and so there is usually a sense of urgency in the advice: 'You'd better hurry or you'll miss the bus.' 'You'd better ring your parents - just in case they're worrying about you.'
To give advice on a general situation or to say that one course of action is better than another one, use should, ought to or it would be better to: 'Parents should teach their children to be kind to animals.' 'Rather than complain and risk upsetting her, it would be better to say nothing.'
II
adjective
BAD : German cars are more expensive but they are more better.
GOOD : German cars are more expensive but they are better.
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good, better, best