根据句意，用括号内所给单词的适当形式填空。
1. I like P.E. best. Because my P.E. teacher is very ________ (friend) to us.
2. — Where is your bedroom? — It's on the (two) floor.
3. — Thank you for your help. — It's my ________ (please).
4. All the books are on these ________ (shelf). You may go to find it.
5. Kangkang likes ________ (dance) at the party, because it's interesting.
