might have done "本来可能……;本来应该或可以做某事"(实际没有发生;含有轻微的责备语气。 should/ought to have done "本来该做某事"(而实际未做) should not/ought not to have done "本来不该做"(实际却做过了,含有责备语气)needn't have done "本来不必做"(但是...
(If sb had done sth, he would never have done sth) Google, a once obscure, ailing / fragile company, would never have achieved today's stunning success, never have conquered so big a market share, if it had ignored the importance of group discussio...
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