Complete the sentences with the given words in their suitable forms. (用所给词的正确形式填空)
1. I think there _______ (be) fewer trees next year.
2. He (collect) 300 pictures since 5 years ago.
3. Sam always (help) his classmates last term.
4. Would you mind _______ (play) games after school?
5. My father came into the bedroom while I _______ (dance).
6. If you want to cross a street, you _______ (wait) for the green light.
7. American fast food seems _______ (be) the most popular in the world.
8. They ______ (eat) a lot of potatoes yesterday, so did I.
9. My mother made me (clean) my room all by myself yesterday.
10. Please look carefully before you _______ (cross) the street.
