求助：XDF-section15-Q16 (新东方蓝皮;大全没有)

Q16

Gas hydrates, chemical compounds of water and natural gas, are increasingly being studied for their potential to be huge reservoirs of energy, possibly causing sea floor instability, and significant contributors to global warming.

A. to be huge reservoirs of energy, possibly causing sea floor instability, and

B. to be huge reservoirs of energy, possibly causing sea floor instability, and even as

C. as huge reservoirs of energy, possibly causing sea floor instability, and

D. as huge reservoirs of energy, and the possible cause of sea floor instability,

E. as huge reservoirs of energy, as possible causes of sea floor instability, and even as

答案 A

“and”不可缺=>排除D

“even as”多余=>排除BE

剩下AC就是to be和as的区别,最后我选了C。想请教一下是不是ETS偏好to be的使用，还是这里有什么固定搭配。请牛牛指点

晕

我也搞不清AC

应该是固定搭配吧,

从意思上理解,to be 有前者是后者的意思,as是作为的意思

个人意见,仅供参考

potential:the possibility to develop or achieve something in the future...

可能因为这个所以用to be 吧

google了一下原文，

What they had were bits of gas hydrates--chemical compounds that are increasingly being studied for their potential as huge reservoirs of energy, as possible causes of sea floor instability, and even as significant contributors to global warming. Scientists had long speculated about them and even made them in the laboratory, but until now only a few had been seen in nature.

看来原文著者还是选E啊