You
are quite right in suggesting that do is used as an auxiliary
verb in questions and negative sentences, like these:
'Do you like sugar in tea and coffee?'
'Did you see Mary last night?'
'What did she tell you?'
'Did you do your homework?'
'I like sugar in coffee but I don’t like sugar in tea.'
'I »å¾±»å²Ô’t do all my homework.'
'I »å¾±»å²Ô’t see Mary.'
' I »å¾±»å²Ô’t even phone her so she »å¾±»å²Ô’t tell me anything.'
Strong
emphasis
You
are also quite right in suggesting that do is not normally
used in affirmative sentences. However, it is used when we want
to place strong emphasis on what we are saying to show that we feel
strongly about it in a positive way. In all these cases, do
is pronounced with strong stress. Consider the following:
'I do like sugar in my coffee! Loads of it!'
'He does look smart in his new suit.'
'You may not realise it, but I do love you.'
'I did enjoy Sue’s cooking last night. What a delicious
meal she served us!
Contrastive
emphasis
There
are three other circumstances when do is used in affirmative
sentences or clauses.
It is used for contrastive emphasis when we want to contrast one
set of circumstances or point in time with another. Study the following:
'I wish I could lose some weight.' 'Yes, well you do eat
rather a lot of sweet things.'
'Why »å¾±»å²Ô’t you ask him for a loan?' 'I did ask him,
but he said he had no money.'
'I hardly ever see my ex-wife, but I do see my children
every week.
Polite
Imperatives
It
is sometimes used with imperatives when we want to make a suggestion
or invitation more polite or welcoming. Study the following:
'Do have some more strawberries! Help yourself!'
'Do come in! Do sit down!'
'Do be careful on holiday! ¶Ù´Ç²Ô’t take any risks!'
'Do write and tell us how you’re getting on!
Avoiding
repetition
It
is often used when we want to avoid repeating a verb which we have
already used in the first part of the sentence. Consider the following:
'Can I have another go with your game boy?' 'Yes, do!'
'She said she’d help me with the ironing and she did!'
'Did you see Maria when she was over in London?' 'Yes,
I did!'
