用括号内所给动词的适当形式填空。

1. The report shows that some animals can _____ (train) to work for people.

2. Those dried flowers _____ (not sell) as well as the fresh ones.

3. Where is Jim? I'm afraid he _____ (forget) the visit to the museum.

4. The passengers were told that the plane _____ (take) off in two hours because of the bad weather.

5. —It is reported the police searched the whole building yesterday but nothing unusual was found there.

    —Really? I _____ (think) the thief had already been caught.

6. In order to complete the task, all the club members had no choice but _____ (stay) up late.

7. He failed the math exam again because the bell _____ (ring) before he finished the rest half of the

    testing-paper.

8. Many scientists are always trying to devote themselves to _____ (study) in different areas.