21、In ___ year 751, the Chinese traveler Du Huan was taken __    _ prisoner by the Arabic army．

A．a, the         B．/, the         C．the, a           D．the,/

20、Everyone agrees that the Philippine police ____    for the tragedy that Hong Kong tourists were killed．

A．are to blame                              B．are to be blamed

C．are being blamed                          D．have blamed

19、Depression is the leading cause of suicide, __     __ in turn is the third leading cause of death among 15 to 24 year olds in the United States．

A．who           B．which          C．that         D．what

18、All the drivers have been warned that driving after drinking shall __    __ serious accidents．

A．bring up           B．bring back           C．bring in         D．bring about

17、—George, ___    _ you sing so loudly at such a late hour?

—I am terribly sorry．

A．will            B．may            C．must           D．shall

16、The truly homeless are the rich who __     _ their home into a hotel hall．

A．will turn                                    B．turned

C．are turning                                   D．have turned

15、__        is well known is that Africa had contacts with India and the Red Sea civilizations from the earliest times．

A．As            B．It             C．What            D．That

14、__       three times in a row, the boxer decided to make a fourth attempt, though．

A．Having defeated                                     B．To have defeated

C．Having been defeated                               D．To defeat

13、Not until they left school ___      how much their teachers loved them and helped them．

A．they realized                                  B．did they realize

C．they had realized                                  D．had they realized