According to the survey, two thirds of the area__________covered by trees now and 90% of the population__________contributions to the Greening Project in the city.

A．is ; has made

B．are; have made

C．is; have made

D．are; has made

氯乙烯可引起的法定职业肿瘤（）。

A.肝血管肉瘤

B.肺癌

C.皮肤癌

D.鼻咽癌

E.喉癌