19、The site is fairly near the city center, ______ it can only be reached by a series of narrow streets．

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

18、—I have ______ high temperature and ______ sore throat．

—Well, you may have the flu．

A．a; a            B．the; the            C．the; a           D．a; the

17、One recent prediction is that within the next 50 years, it ______ possible to link the human brain directly with a computer．

A．is                   B．will be                   C．would be                 D．was

16、With so little time ______ on math, it is all too easy for children to ignore practicing mathematics, which is a kind of language．

A．spent          B．being spent            C．to spend          D．was spent

15、Even if there is no scientific proof yet ______ secondhand smoke causes cancer, there is no reason why nonsmokers should be forced to take this risk．

A．which          B．that         C．when           D．where

14、—Do you know when Phil's coming?

—He ______ 4: 00．

A．says           B．has said           C．had said         D．said

13、You ______ very fast if you went from New York to Boston in six hours．

A．should drive                                       B．would have driven

C．may drive                                        D．must have driven

12、—How did he break his head while swimming?

—______ my warnings, he dived straight into the shallow water．

A．To ignore               B．Ignored             C．Ignoring               D．Being ignored

11、Napoleon would have taken over the world if he ______ the Battle of Waterloo．

A．wins         B．won        C．had won        D．has won

10、—Can you tell me what time the flight to Detroit leaves?

—I'm sorry, but it ______．

A．has been canceled                     B．had been canceled

C．has canceled                            D．had canceled