根据句意，用括号内所给词的适当形式填空。

1. There are some ______(piano) in the room.

2. What club do you want _____ (join)?

3. May I _____ (swim) here?

4. His mother is a ______(music).

5. That is ______ (we) classroom.

新生儿生后排出的胎便由______、______及______组成，呈墨绿色。