21、The @ symbol was used to show the cost or weight of something     it became the standard symbol for e-mail．

A．though    B．since    C．when   D．before

20、Not until I had arrived home       my appointment with Michael Smith．

A．did I remember                              B．that I remembered

C．when I remembered                       D．had I remembered、

19、―Will it snow any more?

―       ．We have had enough this year．

A．I hope so               B．I find not            C．I think so               D．I hope not

18、When it       air pollution, Beijing faces the three“C”s，cars，coal and construction，which lead to Beijing's thick air pollution．

A．refers to                B．comes to            C．happens to              D．speaks to

17、―Which of the two books will you buy?

―I will buy     ，for I've got some such books．

A．both                      B．either                 C．neither                    D．none

16、Stand over there，       you'll be able to see Tuan Tuan，one of two pandas selected as a gift for Taiwan．

A．or                         B．so                      C．but                        D．and

15、―I didn't do well in the exam yesterday．Of course I      for it．

―Oh，you poor fellow! But I think you should learn a lesson．

A．hadn't studied                          B．haven't studied

C．wasn't studying                       D．wouldn't study

14、An Iraqi reporter during a news conference    threw his shoes at Bush and called him a dog in Arabic shocked the world．

A．who                      B．where                C．whom                    D．which

13、At that time, what worried Zhang Yimou most was the weather，which we all know is evidently       anyone's control．

A．above                    B．beyond               C．under                     D．over

12、        Liu Xiang had not hurt his foot, he would have Won the race．

A．If    B．Since    C．Though   D．When