if he _____ the doctor's advice ,he wouldn't have been in such poor health.
问题描述：
if he _____ the doctor's advice ,he wouldn't have been in such poor health.
A)followed
B)has followed
C)was following
D)had followed
请问答案为什么选D,可以回答的详细一些么,可以写出if在各种情况下的用法么,谢谢~
答
对过去的虚拟,固定搭配,从句if had done, 主句 would have done
意为：如果他之前听从医生的建议,现在身体状况就不会这么糟糕.您好，请问在现在，将来的情况下if怎么用啊，谢谢了~与现在事实相反:从句: 动词的过去式（be的过去式一般用were） 主句:would/ should/ could/ might + 动词原形与过去事实相反 : 从句 :had + 过去分词主句 :would/ should/ could/ might + have + 过去分词与将来事实相反 :从句:动词过去式，should + 动词原形，主句 :were to + 动词原形 would/ should/ could/ might + 动词原形