spend on 与 spend in的区别：
spend on是指在什么事上花费了时间，后面接的是名词；而spend in doing是指在做什么事上花费了时间，后面接的是动词-ing。
spend on 与 spend in的用法：
spend in doing something
或spend in somewhere
在…上花费
I spent a week in Spain this summer.
今年夏季我在西班牙度过了一星期。
Don't spend such a lot of time in dressing yourself.
别花那么多时间来打扮自己。
He spent much time correcting my grammar.
他花了很多时间来改我的语法错误。
spend on something 把…花在…
He doesn't spend much time on his homework.
他花在作业上的时间不多。
