Here are the correct forms of the given words in the sentences:

**Exercise 3: Put the verbs into the Past Simple or Past Perfect tenses.**

1. He **was** in prison for twenty-seven years last year.
2. The policeman **told** us to come back in two hours yesterday.
3. My aunt and I slowly **walked** back to the house last night.
4. We **saw** a small grocery store three weeks ago.
5. I (not go) **did not go** to the office last Monday.
6. She (get) **got** married a few months ago.
7. I (finish) **finished** my homework before 10 o'clock last night.
8. Before he came to Ha Noi, he **lived** in Da Nang.
9. They (wait) **waited** at the station for 90 minutes when the train finally arrived.
10. The storm destroyed the sandcastle that we (build) **had built**.

**Exercise 4: Put the verbs into the Past Simple or Past Continuous.**

1. What were you doing when I phoned you? - I **was having** a bath.
2. Mary **was watering** the flowers at 3:00 p.m. yesterday.
3. Peter and I **were doing** the exercise at this time last night.
4. When I **arrived** at this house, he still... (incomplete sentence).

Feel free to ask if you need anything else!