用所给词的适当形式填空。

1. Do you learn English by _____ (watch) English-language videos?

2. What about _____ (listen) to tapes?

3. We get _____ (excite) about something.

4. Do you know the best way _____ (learn) English?

5. He finds watching English movies _____ (frustrate).

土的工程分类是按下列（）原因来分类的。

A.坚硬系数

B.质量密度

C.坚硬程序

D.开挖方法

E.使用工具