用括号内所给单词的适当形式填空。
1. —How big are the manatees?
—They're about on __ (foot) long and 1, 000 pounds heavy.
2. It was __ (discover) that pandas were endangered.
3. —What are they doing?
—"They are trying _______ (help) the environment.
4. We should take our own bags when _______(shop).
5. I was _______ (surprise) to see Jim at the party. I thought he was in hospital.
6. Visiting zoos are like to read _______ (live) textbooks for young people.
7. Do you know what place is _______ (suit) for tigers to live in?
8. The environment _______ (pollute) is more and more serious.
9. My elder brother decided to go abroad to continue his _______ (educate).
10. The Students' Union urges all the students __ (stop) chewing gum.
