очень срочно ,помогите пожалуйста!

Complete with the Past Simple or the Past Perfect Simple of the verbs in brackets.
1. By the time I__ (open) the door, Sam had left.
2. Tony __(collect) 2000 stamps by the time he sold his stamp collection.
3. Susan __(not do) her homework by 7 o’clock last night.
4. I had already cooked dinner when Kelly ___ (invite) me to a restaurant.
5. Judy___ (already / water) the plants by the time the rain started.
6.Martha had posted the letters before __ (see) her.