题目内容：

用所给动词的适当形式填空，每词限用一次。

encourage,  master,  boil,  prevent,  perform, talk back

1.Nobody ____________ waster water from polluting the river unless something is done.

2.My friend Tom ___________ about 1,000 Chinese words in the past 3 months.

3.Tom regretted ______ to his teacher.

4.--- Where’s your mom, Mary?

--- Sorry, I don’t know. Maybe she _________ some soup in the kitchen.

5.Studying is the most important to teenagers. They shouldn’t ______ to work part-time.

6.The actor __________ a funny comedy and made us all laugh.