__ he fail to come over,what could we do without him?For you see,we don't have the key to the lab!

问题描述:

__ he fail to come over,what could we do without him?For you see,we don't have the key to the lab!
A If B should C Whether D unless

选B
这是虚拟语气,表假设的.正常的句子应该是:If he should fail to come over,倒装之后就把if省掉,把should提前了.if + should构成虚拟语气你怎么知道要道装不倒装也是对的,但你的这个句子用的就是倒装啊,我看出来的。怎么看呢》》》????首先通读整句对话,理解到是假设句,就是说,如果他不来,我们就进不去,因为我们没有实验室的钥匙。本来想选if的, 但看到第二句用了个could,就说明第一句肯定是虚拟语气了。 如果选if,那he后面还得用个should, 但选B就OK了,只要把should提前,if就可以省略。