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.[ ]

_____ are you staying in Tibet? — Just for four days. [ ]

Must I feed the goldfish now? — No, you ______. But you must do it before supper.

I can still remember ______ it was so long ago.

_____ is your mother?-She is fifty.[ ]