问题

Were you worried about him last night? — Yes. It was ________.
A:until he returned that I went to bed
B:until be returned that l slept well
C:not until he returned that I went to bed
D:not until did he return that I went to sleep
B:until be returned that l slept well
C:not until he returned that I went to bed
D:not until did he return that I went to sleep
正确答案是: