问题补充：
It was back home after the experiments.
A. not until midnight did he go
B. until midnight that he didn’t go
C. not until midnight that he went
D. until midnight when he didn’t go
答案：
A. not until midnight did he go
B. until midnight that he didn’t go
(答案→)C. not until midnight that he went
D. until midnight when he didn’t go
解析：
考查not until的强调句。 not until的强调句必须写成it was/is not until +陈述语序。所以排除A,B,D, “直到半夜实验后他才回家。”
