This is not an economical way to get more water; ____, it is very expensive.

Many teenagers show interest in the books that are written ________ Guo Jingming.—That’s true. My son says he can get what he thinks and wants in his books.[ ]

Tom and I went boating yesterday. _______ had a good time.

Write a note _____ a friend. [ ]

This is my good friend(朋友).—________ name is Tony.