题目内容
17. ―What a pity! Their experiment is a failure.
―They better under more favourable conditions.
A. should have done B. could have done
C. must have done D. may have done
17. B考查含蓄的虚拟条件句。句意:"真遗憾!他们的实验失败了。""在更加有利的条件下,他们本能做得更好。"这里under more favorable conditions是一个隐含的虚拟条件句, 相当于if they had been under more favorable conditions。 这是和过去事实相反的虚拟条件句,所以主句用could have done的形式。could have done表示过去原本能够做某事而实际上并没有做。所以选B。
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