根据汉语提示，用词组的适当形式填空。

1. A key is ______ (用来) opening and locking a door.

2. There are some ______ (少先队员) in the picture.

3. We must ______ (向……学习) each other and help each other.

4. Mr. Mott was in the meeting room ______ (刚才).

5. Today Mum is going to cook ______ (一些美味的东西) for us.