在英语学习中，好多同学对如何使用whether和if感到模糊，常常误用。下面我们分别来看一下whether和if的用法。

一、只用whether的情况：

1在表语从句和同位语从句中只能用whether表“是否”。如：

He answered my question whether he would come . The news whether our team has won the game is not known. The question is whether the book is worth baying.

2当主语从句位于主语位置上时，只能用whether表“是否”。如：

Whether it will rain is not clear . Whether they will come in time is a question . 3在介词后面引导宾语从句表“是否”，只能用whether。如：

It all depends on whether they will support us . The discussion focused on whether they would buy a new car . 4后面直接跟动词不定式时，只能用whether表“是否”。如：

I don’t know whether to stay or not. . 5后面紧跟or not时。如：

We didn’t know whether or not she was ready . 6引导让步状语从句时，只能用whether。如：

Whether you like it or not ,you must do it well . 7用if会引起歧义时。如：

Please let me know if you like it . 这个句子可有两个意思：“请告诉我你是否喜欢。”或“如果你喜欢，请告诉我。”用whether就可以避免歧义。

二、只用if的情况1引导条件状语从句时。如：

If it doesn’t rain tomorrow , we will go hiking . If you like it , you can take it . 2和even连用时。如：

Even if the job was difficult , they did it well . Even if it’s sunny , it a bit cold .

三、if , whether均可使用的情况1引导宾语从句。如：

I wonder if / whether the news is true or not . 2在“be +形容词”之后。如：

He was not sure if / whether it is right or not . 3主语从句中使用了形式主语it，主语从句后置时。如：

It hasn’t been decided if / whether we shall have a class meeting .