题目内容：

填入所给单词的适当形式

1.At times this balance of nature ___________ (disturb), which results in a number of possibly unforeseen effects.

2. With his mind _____________ (focus) on the things not related to his studies, his marks have fallen rapidly.

3.When _____________(compare) with the size of the whole earth, the highest mountain doesn’t seem high at all.

4. Students should be encouraged_____________(present) their own opinions, whether right or wrong.

5. Walking along the river bank one day, I found a child ___________ (struggle) in the water.

6.The plan__________ (design) to encourage the employees to improve their work turned out to be a success.

7.The mobile phone _____________(guarantee) for at least five years, but it went wrong only one year later.

8. It’s high time someone ______________(protest) against human rights violations.

9.A sheep ___________ (feed) on this kind of special grass usually grows much faster than one on ordinary.

10.Some students have no idea of why they are studying, so they are _________ (aim) most of the time.