你会正确使用虚拟语气的倒装形式吗

请看典型考题：__________ your address,I would have written to you。 A。 Did I know B。 Were I to knowC。 Had I known D。 If I should know此题应选 C。这是虚拟语气的倒装形式。当虚拟条件句中含有 were,had,should,could等动词时,可以将if省略,然后将 were,had,should,could 等词移至句首：1。 If he should fail,he would kill himself。 →Should he fail,he would kill himself。 万一失败,他就会自杀。2。 If I were you,I would do it at once。 →Were I you,I would do it at once。 假若我是你,我就会马上做。3。 If I could do it,I would。 →Could I do it,I would。 要是我能做此事,我一定会做。4。 If he had seen you yesterday,he would haveasked you about it。 →Had he seen you yesterday,he would haveasked you about it。 他昨天要是看到了你,他就会问你这事了。