题目内容:
Again as __________ in this experiment, he didn′ t lose heart.
A.he failed
B.did he fail
C.he did fail
D.had he failed
参考答案:
答案解析:
Again as __________ in this experiment, he didn′ t lose heart.
A.he failed
B.did he fail
C.he did fail
D.had he failed