关于PREP的两道题中的句子结构

After several year of rapid growth,the health care company became one of the largest health care providers in the metropolitan area,while it then proved unable to handle the in business,falling moths behind in its payment to doctors and hospitals.
A)while it then proved unable to handle the in business,falling moths behind in its payment to
B)while it then proved unable to handle the in business and fell moths behind in its payment to
C)but then it proved unable to handle the in business,falling moths behind in its paying
D)but then proving unable to handle the in business,falling moths behind in paying
E)but then proved unable to handle the in business,falling moths behind in paying
我选的是C，答案是E

Whereas the honeybee's stinger is heavily barbed and cannot be retracted from the skin, because the yellow jacket has a comparative smooth stinger,it is therefore able to be pulled out and used again.
A)because the yellow jacket has a comparative smooth stinger,it is therefore able to be pulled out and used
B)the comparative smoothness of the yellow jacket's stinger allows them to pull it out and therefore use it
C)the yellow jacket's stinger is comparatively smooth,and can thereforebe pulled out and used
D)in comparison,the yellow jacket's stingeris smooth,and thus able to be pulled out and used
E)in comparison,the yellow jacket has a smooth stinger,thus allowing it to be pulled out and used
我选的是E，答案是C

这两题一上来我就把正确答案给排除掉了，之前做GWD，OG觉得只有A do sth,and A（B） do sth 或A do sth and do sth这样的结构才正确。，and /，but 这样的逗号+连词之后应该接一个句子，很晕，希望哪位好心的NN能够讲解下。

第一道，逻辑关系不对，but then it proved是自己证明but then proved是被证明！

i proved to be innocent /i was proved to be innocent 意思不一样！

第二题，考对称平行，前后同类比较.

有了whereas再用in comparison语义重复。~

那but then proved unable to handle the in business,falling moths behind in paying做主句的什么成分呢？

我是这样理解的

1but后是要接句子，但but前后两个句子主语一致，所以but后句子朱育可以省略。

2D E选项把原来的comparative变成in comparison意思有所改变，comparative可理解为相当的，相对的。
in comparison就是比较之下。。。。前面有wheras已经不需要in comparison不然就是语义重复。