The old lady’s hand shook frequently. She explained to her doctor ____this shaking 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

科目 英语   题型 单选题   难度 容易

知识点： 副词的原级比较