if引导的从句是什么从句
if一共引导三种从句
条件状语从句，译为“如果”。
He will come if you invite him.
宾语从句，译为“是否”。
I wonder if she is ill.
引导非真实条件句，使用虚拟语气，译为“假如,要是”。
If I were you, I would never do that.
Put your hand up if you need more paper.
若有人还要纸，请举手。
only time will tell if the treatment has been successful.
只有时间才能证明这种疗法是否成功。
He must be 70 if he\'s a day!
他至少70岁了！
I don\'t care if I never see him again!
即使我永远再也见不到他，我也不在乎！
Call me if you have any problems regarding your work.
你如果还有什么工作方面的问题就给我打电话。
What difference will it make if he knows or not?
他知不知道有什么关系吗？