1. Did he arrive
2. Have you explored
3. Were cooking, was tyding
4. I will take
5. Decided
6. Study, will pass
7. Listened
8. Will be
9. Was watching
10. If I go, I will take
11. Has been working
12. It will get
13. Was reading, when he heard
14. Do people live ?
15. I've been learning
16. If the weather is good, we will go for a walk
17. If people invent, will not pollute