As is known to us, theory is based on practice and servers practice.
A. by chance B. in turn C. in return C. by turn
If you win the competition, you will be given ____ to Europe for two.
| A．a free 7-day trip | B．a free trip for 7-day |
| C．a 7-day free trip | D．a trip for 7-day free |
—What do you think of the book？
—Oh，excellent．It's worth ___________ a second time．
| A．to read | B．to be read | C．reading | D．being read |
The library needs ＿＿, but it will have to wait until Sunday．
| A．cleaning | B．to clean | C．clean | D．being cleaned |
A left-luggage office is a place where bags _______ be left for a short time, especially at a railway station.
| A．should | B．can | C．must | D．will |
Sir, you ______be sitting in this waiting room. It is for women and children only.
| A．mustn’t | B．can’t | C．won’t | D．needn’t |