if引导的倒装句只有一种形式：虚拟条件句中如果谓语动词含有were，should，had这几个词，可以把were，should，had放在if的位置，并去掉if：这就是虚拟条件句的倒装，但已经没有if了。
if
读音：英 [ɪf] 美 [ɪf]
释义：如果，假若，倘若，当，无论何时。
语法：if作为从属连词，可引导条件状语从句、让步状语从句和名词从句。if引导条件状语从句，从句可为真实条件从句，也可为虚拟条件从句。
例句：
She gets very upset if I exclude her from anything.
要是有什么事情我不让她参加，她会非常难过。
扩展资料
if的近义词：whether
whether
读音：英 [ˈweðə(r)] 美 [ˈweðər]
释义：(表示迟疑或两个可能性之间的选择)是否。
语法：whether用作连词，意思是“是否，是不是”，可引导名词从句或动词不定式短语。whether还可引导让步状语从句，意思是“不管，无论”，从句中通常用一般现代时代替将来时。
例句：
It doesn't matter to me whether you go or not.
你去或不去，对我都没关系。
问题解答：
if不能直接引导倒装句，
if引导倒装句时必须将if去掉！
佐证例句：
● If it should snow, I would not go there.
改为：
Should it snow, I would not go there.
● If I had seen him yesterday, I would have told him about it.
改为：
Had I seen him yesterday, I would have told him about it.
● If anyone calls, please tell them I'm busy.
改为：
Should anyone call, please tell them I'm busy.
如：
If he had come yesterday, he would have known it.
=Had he come yesterday, he would have known it.
If I were there, I would help them.
=Were I there, I would help them.
If I should have 200,000 yuan, I would buy a good car.
=Should I have 200,000 yuan, I would buy a good car.本回答被网友采纳
If he had finished it yesterday, he would have handed it in then.
=Had he finished it yesterday, he would have handed it in then.
If I were there, I would help them.
=Were I there, I would help them.
If I should have 200,000 yuan, I would buy a good car.
=Should I have 200,000 yuan, I would buy a good car.
2、if引导状语从句，放在only后面。例如：
Only if you wok harder and do more practice 【can you improve 】 your Englsh.
祝你开如意！