21、______engineers and workers are helping to rebuild the damaged city．

A．Many           B．Much           C．A little             D．A lot

20、Steven and William are keen ______playing computer games．  

A．to                 B．with              C．on                 D．at

19、I knocked on the door several times but ________answered，so I left．

A．somebody          B．nobody            C．anybody           D．everybody

18、Plastic bags have caused serious environmental pollution，________?

A．haven’t they     B．have they        C．don’t they         D．do they

17、The snow storm which hit this area last night was_________ in recent years．

A．heavy         B．heavier           C．heaviest          D．the heaviest

16、We should leave early tomorrow morning，_________we won’t get there on time．

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

15、Bill won’t make any progress ________he studies harder than before．

A．if                 B．when            C．because           D．unless

14、George was frightened to see a snake in the grass．His face turned ___________．

A．pale          B．clean              C．sadly              D．happily

13、After a long journey，the eight pandas from Wolong safely ________in Beijing．

A．arrived       B．reached            C．got          D．come

12、Look! Jane’s grandmother _________with some aged people in the park．

A．dances          B．danced           C．is dancing              D．was dancing