题目内容：

if后面主句的时态
if作如果讲时后面主句用的是将来式或者情态动词 if作是否讲呢?举个例子好不好~

优质解答

if作如果讲时后面主句用的是将来式或者情态动词
如：We'll go to the mountains if the weather is fine tomorrow.
if作是否讲时,后面跟的事态随主句变化,与whether可以互换
如：I don't know if he will come tomorrow.
I didn't know if he would come the day after tomorrow.