五、 改写句子：根据各题所给出的信息补全句子。
1 If it does not rain，they will go to the park.
They will go to the park _ it rains.
2 You must not leave the boy alone.
You must not leave the boy _ .
3 What a tall tree it is!
_ tall the tree is! .
4 Did he enjoy himself in the party?
Did he _ in the party?
5 Everybody knows he is a good teacher.
He is _ to be a good teacher.
