Using "Do, Does and Did"

1. Martha always does his homework on time.
2. Volunteers do a lot of work around the hospital.
3. Jasper did a great job on his history report for school.
4. You have done nothing all morning!
5. I am doing the best I can!

Negative sentences with do not, does not and did not

When creating negative sentences, we usually use shortened forms: don’t, doesn’t and didn’t together with the base form of the verb.

Note: Save the long forms (do not, does not and did not) for when you want to create emphasis. When speaking, you would put an accent on the ‘not’.

1. Your client doesn’t understand the contract.
2. You don’t need to worry about me.
3. Your friends didn’t get the e-mail.

For more information

http://www.gingersoftware.com/grammarbook/verbs/do-does-did/