is often the case with children Amy was better by the time the doctor arrived. A. It B.

问题补充：

is often the case with children, Amy was better by the time the doctor arrived.

A. It

B. That

C. What

D. As

答案：

A. It

B. That

C. What

(答案→)D. As

解析：从句置于句首只有引导词as 可以。as引导的为限制性定语从句，as在句中作主语，指代后面的整个句子。句意：就像孩子们常有的情况一样，等大夫到了艾米的情况就好多了。

【考点定位】考查定语从句