If computers______, many problems on space flight could not have been solved.A、h

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问题 If computers______, many problems on space flight could not have been solved.

选项 A、had not been invented
B、are not invented
C、were not invented
D、have not invented

答案 A

解析译文：如果没有发明计算机的话，太空飞行的许多问题就不可能解决。虚拟语气题。本题考查与过去事实相反的虚拟语气，其结构为“从句：If+主语+had+动词过去分词；主句：主语+should／would／might／would+have+动词过去分词”，故本题选[A]。

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