117. Feeling more and more pressure from the environment _______, the government has decided to close down the factories pouring out poisonous chemicals.

A．polluted

B．having polluted

C．being polluted

D．having been polluted

极昼极夜现象出现的范围是 [ ]

A．南、北极圈之间

B．南、北纬66.5°的纬线圈上

C．南北极圈至极点的地区

D．南北极点上