试题题干
Translate the following sentence into Chinese.
He watched very carefully and acted till all had left the house, and it was difficult to catch him in the act.
参考答案
试题解析
考点：carefully小心地；it was difficult to···做某事是困难的；catch抓住。
句子结构：句子为并列句。前半句中till all had left the house为时间状语从句，后半句主干为it was difficult to catch him。