GWD-23-Q23之逗号后缺主语的问题！

EMMALIULIU

After several years of rapid growth, the healthy 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.

• while it then proved unable to handle the increase in business, falling months behind in its payment to
• while it then proved unable to handle the increase in business and fell months behind in its payment to
• but then it proved unable to handle the increase in business, falling months behind in its paying
• but then proving unable to handle the increase in business, falling months behind in paying
• but then proved unable to handle the increase in business, falling months behind in paying
  

正确答案是E。

其他都理解，就是不明白“，+but”结构后面竟然没有主语。这里既没有插入语，也不是举例，为什么可以“，+but”后跟不完整句子？

bejamin1111

你发帖啦。。。参考下我们的原始讨论哇