spend v. 花费； 度过 

spend time/money on sth.；spend time/money (in) doing sth.

度过时间/花费金钱做某事（主语为人、宾语为时间/金钱）

They should spend their time on schoolwork. 他们应该花费时间在功课上面。

pay v. 付钱 

pay for sth. 付……的钱（主语为人、宾语为金钱）

I have to pay for the lost book. 我不得不赔偿丢失的书。

take v. 花费 

It takes sb.+时间+to do sth. /(Doing)sth. take(s) sb. some time

做某事花费某人多长时间（主语为It/事物、宾语为金钱）

It took them three years to build this road. 他们用了三年时间修建这条马路。

Repairing this car took him the whole afternoon. 他花了一下午修车。

cost v. 值  

sth. cost (sb.)+金钱 

某物花了(某人多少钱) （主语为物、宾语为金钱）

A new computer costs a lot of money. 买一台电脑要花一大笔钱。

spend主语是人，cost主语是物，take主语是it，pay的主语也是人。