The old lady's hand shook frequently. She explained to her doctor ______ this shaking

Question

had begun half a year before, and ______, only because of this, she had been forced to give up her job.
A when; how
B how; when
C how; how
D why; why
请问为什么选择C？

Answer 1

B
第一空 半年前这种颤抖是怎么开始的
第二空 那时候，就因为这个，她被迫放弃工作。追问

我想说的是答案是C……

追答

第二空选How 表示怎么样了。。。

Answer 2

这个有上下文吧！？追问

没有，这是一道单项选择题。