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 ________ (three) floor.

3. —Thank you for your help.       —It's my _______ (please).

4. All the books are on these _______ (shelf). You may go to find the book you want to borrow.

5. Kangkang likes _______ (dance) at the party, because it's interesting.