用括号内所给单词的适当形式填空
（1）What a____ (please) it is for me to play the piano with you!
（2）Mother asked the Greens to help____(they) to some pears.
（3）Tim sings even____ (badly) than before.
（4）He felt____ (true) sorry for what he said.
（5）____ (clean) work is to make our city clean.
