用括号内所给单词的适当形式填空。

1. It's interesting _____ (help) my mother do the housework.

2. He made a kite _____ (make) his daughter happy.

3. My dream is _____ (be) a scientist one day.

4. We went to the theatre _____ (watch) a play.

5. There are many ways _____ (save) animals in danger.

外壳为正极、中心引线为负极的二极管，称为（），管壳底上注有黑色标记。