Unit 5. Past Simple (I did)

Very often the past simple ends in -ed (regular verbs):

• I work in a travel agency now. Before that I worked in a shop.
• We invited them to our party but they decided not to com.

But many verbs are irregular. The past simple does not end in -ed. 

• Mozart wrote(write→wrote) more than 600 pieces of music.
• We saw(see→saw) Rose in town a few days ago.
• I went(go→went) to the cinema three times last week.
• It was cold, so I shut(shut→shut) the window.

In questions and negatives we use did/didn't + infinitive.

• When did Mr Thomas die? / About ten years ago.
• They didn't invite her to the party, so she didn't go.

Be careful when do is the main verb in the sentence.

• What did you do at the weekend? ( not 'what did you at the weekend' )
• I didn't do anything. ( not 'I didn't anything.' )

The past of be (am/is/are) is was/were

Note that we do not use did in negatives and questions with was/were.

• I was angry because they were late.
• Was the weather good when you were on holiday.
• They weren't able to come because they were so busy.
• Did you go out last night or were you too tired?