If the balance of nature is ____ , a series of problems will arise .

moon cake is really delicious. Can Ihave another piece —________, since you are at your closefriend’s home.

In order to _____ a good command of German, she quitted her job and went to study in Germany.[ ]

Our voyage to Iceland cost alot of money． 一Didit well．that doesn’t matteryou enjoy yourselves．

The book __ by him is difficult __.