什么时候可以转换成IF?结合两者说明一下!~谢谢!~

whether和if的意思相同，都是引导名词从句的连词，一般情况下可以互换使用。
但在下列情况下，whether不能if被取代:
1) whether引导主语从句并在句首时；
e.g. Whether the plan is feasible remains to be proved.

2）whether引导表语从句时（因为if不能引导表语从句）；
e.g. The point is whether we should lend him the money.

3）whether从句作介词宾语时；
e.g. I worry about whether he can pass through the crisis of his illness.

4）从句有"or not"时.
e.g. I don't care whether you like the plan or not.