—I’m afraid that I can’t do it.—Oh, you should believe in yourself. You won’t know what you can do______ you try it.

_______ they are twin brothers, they don’t look like each other.

It took me two weeks ____ reading the novels written by Guo Jingming. . 

The bike is very old, ________ he likes it very much.

---Mum, I’m leaving for Beijing tomorrow morning.--- Oh, good. But be sure to phone me _______ you get to Beijing, please.