spend：（花錢+on、花時間+in）
1、sb. spend some money on sth.
eg.I spend 1 yuan on the pen.
2、sb. spend some time in doing sth.
eg. He spends two hours in finishing his homework.
3、sb. spend some time in (doing) sth.(重點)
eg.Though I spend much time in math ,I still got "c" for it.
(誤區：一般人認為表sth.的"math"前應加on，但是這裡是把math前的動詞省略的緣故造成的誤區。判斷方法：表花時間做某事用in，花錢買某物就用on，這個應該很快就能判斷出來了，就不會造成誤選，這是考試最常考到的，要注意啊)
cost（+to do）
1、sth. cost sb..(賓語形式) some money.(花錢買某物)
eg.This book cost me 10 dollars.
2、It cost sb.(賓語形式) some time to do sth.（花時間做某事）
eg.It cost me 2 hours to finish the homework.
pay（+for）
1、sb. pay some money for sth.（ 某人花錢買某物）
eg: I pay 10 dollars for this book.
希望以上歸納對你有用啦。。。
spend：（花錢+on、花時間+in）
1、sb. spend some money on sth.
eg.I spend 1 yuan on the pen.
2、sb. spend some time in doing sth.
eg. He spends two hours in finishing his homework.
3、sb. spend some time in (doing) sth.(重點)
eg.Though I spend much time in math ,I still got "c" for it.
(誤區：一般人認為表sth.的"math"前應加on，但是這裡是把math前的動詞省略的緣故造成的誤區。判斷方法：表花時間做某事用in，花錢買某物就用on，這個應該很快就能判斷出來了，就不會造成誤選，這是考試最常考到的，要注意啊)
cost（+to do）
1、sth. cost sb..(賓語形式) some money.(花錢買某物)
eg.This book cost me 10 dollars.
2、It cost sb.(賓語形式) some time to do sth.（花時間做某事）
eg.It cost me 2 hours to finish the homework.
pay（+for）
1、sb. pay some money for sth.（ 某人花錢買某物）
eg: I pay 10 dollars for this book.
希望以上歸納對你有用啦。。。