Again as _________ in this experiment, he didn&39;t lose heart。
A.he failed
B.did he fail
C.he did fail
D.had he failed

A.he
B.did
C.he
D.had

【参考答案】

A
考查让步状语从句，as/though引导的让步从句必须将表语或状语提前(形容洞，副词，分词，实义动词提前).......

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