86OG-31(cd22-29)求教，以前没讨论过

答案是A,不知道C为什么不对，

(C) Trying to recover uranium out of seawater may someday be worthwhile,but at present this process is prohibitively expensive.

不是更对称吗？

It may someday be worthwhile to try to recover uranium from seawater, but at present this process is prohibitively expensive.

(A) It may someday be worthwhile to try to recover uranium from seawater

(B) Someday, it may be worthwhile to try and recover uranium from seawater

(C) Trying to recover uranium out of seawater may someday be worthwhile

(D) To try for the recovery of uranium out of seawater may someday be worthwhile（A）

(E) Recovering uranium from seawater may be worthwhile to try to do someday