be used as .be used to .be used for .be used to doing.used to doHe a teacher,but now he is businssmanThe locks locking the doorsJapanese the second foreign language in many universities in ChinaPeople surfing the Internet nowWood can make paper

used to be
are used for
is used as
is used to
be used to
其实这里面，您只需要区分 used to do 和 be used to doing 这两个固定用法就可以了。前者是过去习惯于做某事，但是现在不了；后面的是通常习惯于做某事。其他的，很好理解了。

1 used to be 过去常常……
2 is used for 被用作……
3 is used as
4 are used to 习惯于……
5 be used to
加油！不明白再问！如果帮到你，请采纳，谢谢！

be used as 被用来当做作...be used to 被用来作....be used for 为了什么被使用.be used to doing.习惯于做...used to do 过去常常做某事（现在不做了）
He used to be a teacher,but now he is businssman
The locks are used for locking the doors
Japanese is used as the second foreign language in many universities in China
People are used to surfing the Internet now
Wood can be used to make paper