单选题 _________ , Shirley thought Carol's husband was ill, but later she realized he wasn't.

【正确答案】 B
【答案解析】[汉译] 起初，雪莉以为卡洛尔的丈夫生病了，后来才得知不是这么回事。
[注释] 介词词组“ATFIRST”做状语，意思是“起初，原先”。