请教while用法以及GWD23-Q23

glitters

请问做转折意思时while和but有什么区别?
为什么下面这道题不选B呀？
223.    (30372-!-item-!-188;#058&005388)    (GWD-23-Q23)

After several years 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 increase in business, falling months behind in its payment to doctors and hospitals.
A. while it then proved unable to handle the increase in business, falling months behind in its payment to
B. while it then proved unable to handle the increase in business and fell months behind in its payment to
C. but then it proved unable to handle the increase in business, falling months behind in its paying
D. but then proving unable to handle the increase in business, falling months behind in paying
E. but then proved unable to handle the increase in business, falling months behind in paying
答案为E

chy48339145

while的转折有对比含义，而且要同时发生，跟then冲突，所以A,B都不能选
but then=on the other hand,固定搭配，主语相同时可省

葛佳

while 转折还要同时发生？
这个是知识盲点
thank ls
但是D,but then proving unable[CH1] to handle the increase in business, falling months behind in paying

[CH1]but后面接句子  ?为啥要解句子？怎么不对了
E也没有结句子啊？

pansean

这题已经被详细讨论过，参考如下
http://forum.chasedream.com/GMAT_SC/thread-353398-1-1.html?userid=323284