Only after he realized the significance of mastering two languages English carefully.A. d

Only after he realized the significance of mastering two languages English carefully.
A. did he set about learning
B. did he set out learning
C. had he set about learning
D. had he set out learning

(答案→)A. did he set about learningB. did he set out learningC. had he set about learningD. had he set out learning解析：考查部分倒装句和词组：句意：只有在他意识到掌握两门外语的重要性后，他才开始认真学习英语。only+副词/介词短语/状语从句，放在句首时，主句用部分倒装，be动词，情态动词，助动词放在主语前面，realize和set out是同时发生，所以用过去时，排除CD项，而且set about doing是开始做什么，set out后面接不定式做宾语。选A。

你的回答很对