根据句意及首字母提示，完成下列单词拼写。

1. —Sorry, I’m late.

    —That’s all r________.

2. —Are you a teacher, t________?   

    —Yes, I am.

3. This is Mary. She is my good f________.

4. I can s______ the ABC song.

5. Jeff is an English boy. Is he your b________?

控制声源辐射的技术有（）等等。

A、吸声

B、隔声

C、减振

D、隔振