"" DO ""

"Do" is both an auxiliary and a full verb.

As an auxiliary, we use "do" (and "does") for making questions in the present simple tense.

Do you know what time it is?

Does he live near here?

We also use it in question tags when there is no other auxiliary. 

You don't know him very well, do you?
You like going to concerts, don't you?

As a full verb, we use it to talk about actions or responsibilities.

I do the cleaning every day.
He does the washing-up.

If we ask questions, we need to use the auxiliary "do" as well.

Do you do the cleaning?
Does he do the washing-up?

But we can also use "do" in other ways.

1. To avoid repetition

He doesn't like coffee, but I do. ("do" replaces "I like coffee".)
I asked him to clean the house, which he did. ("did" replaces "clean the house")
Can I have another biscuit? Please do! ("do" replaces "have another biscuit")

2. For emphasis or contradiction

I do like your new dress. ("do" in this type of sentence is emphasised with stress on the "do")

Be careful not to over-use this. You only need "do" (or "does" for third person singular) if you want to say something that is surprising, or contradictory.

You should have told him about the accident.
But I did! (= I told him)

3. To make imperatives more polite and friendly

Do sit down!
Do help yourself to more coffee.

Without the "do", the imperative sounds more like an order.

For the following questions, decide if you need do, does, did (or nothing) in the sentences.

1. __ we have to go to the dentist again?

•  Does
•  -
•  Do

2. Yes, we __

•  have
•  does
•  do

3. __ tell me all about your holiday!

•  Do
•  Does
•  Did

4. You __ know what time the concert starts, do you?

•  do
•  don't
•  -

5. __ he always go out at weekends?

•  Do
•  Does
•  -

6. Yes, he _

•  do
•  does
•  goes

7. He told me he would help and he __

•  did
•  told
•  did help

8. You __ come from Spain, don't you?

•  don't
•  -
•  did

9. She doesn't like coffee, __ she?

•  does
•  don't
•  doesn't

10. Don't you __ know what time it is? We have to leave immediately.

•  do
•  don't
•  -