是意思不相同,what class指在什么班,比如艺术班,数学班等。which class指的是在哪一个班。what class所问的班级没有范围限制,侧重于“班级”的种类。
一、修饰名词:
当用作定语修饰其后接名词时,which用于有范围限制的场合,what用于没有范围限制,侧重于种类的场合。如:
Which color do you like, black or white?
Which is bigger, the sun or the earth?
What color is your car?
二、单独使用,后面不加名词:
当其后不接名词时,which和what的用法区别依然是:用于有范围限制的场合,what用于没有范围限制,侧重于种类的场合。如:
What would you like for dinner?
I'd like tomatoes, cucumbers, lettuce and onions.
We have tomatoes, cucumbers and onions.
Which would you like for dinner?
I'd like some tomatoes.
三、与else和of短语连用时:
由于what提问的事物没有范围限制,所以其后可以跟else,但一般不跟表示特定范围的of短语。而which提问的事物有范围限制,所以其后一般不接else,但却常与表特定范围的of短语连用。如:
What else have you bought?
Which of these dictionaries is yours?
长篇大论之后,如果你还是不确定要用哪个,那么这里介绍一个方法,可能不是100%适用,但是适用于大部分。
当你想使用 which 时,试着在 which 后面加 ”of + 代词“,如果行得通,那么就用 which,例如:
Which (of your) shirts are you considering for the photo?
你考虑穿哪件衬衫拍照?
I don’t know which (of your) sisters you are bringing to dinner.
我不知道你要带哪个姐妹来吃饭。
Which (of their) books are they using in class today?
他们今天上课用的是哪本书?
解析:当你试着用 what 去代替 which 之后,你会发现行不通,因为没有类似 what of 结构作主语的。