Ⅰ.单项填空(共15小题；每小题1分，满分15分)
1．Now they have failed in the experiment，we'll have to________ it more carefully.
A．talk about B．go about
C．care about D．come about
【解析】 talk about“谈论，谈起”；go about“着手(做某事)，从事”；care about“关心”；come about“产生，发生”。根据句意“由于他们的试验失败了，我们必须更加谨慎地进行试验。”可知选B。
【答案】 B
