人类大量使用氯氟烃（CFCs），工业上将其用作制冷剂、气溶胶喷雾剂、发泡剂以及氟树脂生产的原料，其造成的全球环境问题主要是（）

A.气候变暖导致冰川融化等生态破坏

B.臭氧层破坏

C.形成酸雨，破坏生态系统

D.生物多样性锐减

E.植被破坏，导致沙漠化

语法填空（每题1分，共10分）

仔细阅读下列短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中单词的正确形式填空。

Nelson Mandela, born ____小题1:____ July 18, 1918, is the first black president of South Africa. He studied law____小题2:___ he entered university. In 1944 he founded ____小题3:____ ANC Youth League. Then in 1952 he set up a law office ____小题4:__ ( help ) poor black people. Because of his ____小题5:____( fight ) against the government and anti-black laws, he ___小题6:____ ( sentence ) to five years hard labor. Fighters from ANC began to blow up buildings in 1963 ____小题7:____ he was put in prison again for life imprisonment on Robben Island. Twenty-seven years later, he was freed at last by the white government. In 1993 he was made the ____小题8:___ ( one ) black president of South Africa. A lot of people in the world think Nelson Mandela is ____小题9:___ ( real ) a great person. ____小题10:___do you think of him?