Past simple or Past perfect?

1. I (finished / had finished) writing the project at 6 o'clock yesterday.

2. I (wrote / had written) the composition by 6 o'clock yesterday.

3. The teacher (understood / had understood) that the pupils (did not / had not done) their homework.

4. Lucy (threw / had throw) away the letter which Peter (sent / had sent) to her.

5. I (tell / had told) my mum about the marks which I (got / had got) at school

6. He said he (was / had been) there twice.

7. When I (came / had come) to her, she (already went / had already left).