题目内容:
It was _____ the chief engineer came _____ we began the experiment.
A.not until; that
B.not until; then
C.until; that
D.until; when
参考答案:
答案解析:
It was _____ the chief engineer came _____ we began the experiment.
A.not until; that
B.not until; then
C.until; that
D.until; when