6. Supply the Past Perfect or Past Simple in the following sentences.
1. When I left the house, I... (realise) that I... (forget) my keys.
2. She was sad because she ... (fail) the test.
3. I... (not laugh) at the joke because I... (hear) it before.
4. He ... (leave) by the time I got there.
5. When I opened the safe, the money... (disappear).
6 Andrew ... (do) the test before, so he ... (find) it very easy
7. He ... (can not) find his watch. He had lost it.
8. When he ... (arrive) at the station, his train had already left.
9. When she was young, she... (dance) a lot.
10. When we arrived at the furniture shop, they... (sell) the table we... (want).