用所给单词的适当形式填空。 

1. The teachers in our school are _________ ( friend)  to us.  

2. Please _________ ( be) quiet. The teacher is coming.  

3. _________ (leaf) on some trees usually turn yellow in autumn.

4. There are three _________ ( box) of milk on the table.

5. The music sounds _________ ( relax) .