句型转换

1. Is this a ruler?(作否定回答)

____, it ____.

2. Dick is sixteen.(对画线部分提问)

____ ____ is Dick?

3. That's an English book.(改为复数句)

____ ____ English books.

4. They are in Class One, Grade Seven.(对画线部分提问)

____ class are they ____?

5. That is my mom.(对画线部分提问)

____ ____ that?

若扰动产生在系统内部，则叫内扰动。若扰动来自系统外部，则叫外扰动。扰动都对系统的输出量产生影响。