补充题45题（链接中没有）

45.   If industrial pollution continues to deplete the ozone layer, the resulting increase in ultraviolet radiation will endanger human health, causing a rise in the incidence of skin cancer and eye disease, and perhaps even threatening global ecological systems.

(A) and perhaps even threatening

(B) and may even threaten

(C) and even a possible threat to

(D) as well as possibly threatening

(E) as well as a possible threat to

答案是D,为什么A 不可以呢？

threat to sth.

threat在这里做名词，A中的threating是动名词，不如名词好。

至于possible 和perhaps那位大牛能说一下？

那这里threat to 是与a rise 平行吗？

为什么B不对呢？我觉得好像是 endanger human health 与threaten global ecological systems的一个平行

 causing a rise in the incidence of skin cancer and eye disease,  g as well as possibly threatening lobal ecological systems

其中causing 与threatening 平行对称, 选D是因为A中perhaps even表达不对