pay的基本用法：
(1)pay (sb.) money for sth. 付钱（给某人）买……。例：I have to pay them 20 pounds for this room each month. 我每个月要付20英磅的房租。
(2)pay for sth. 付……的钱。例：I have to pay for the book lost.我不得不赔丢失的`书款。
(3)pay for sb. 替某人付钱。例：Don?蒺t worry!I'll pay for you.别担心，我会给你付钱的。
(4)pay sb. 付钱给某人。例：They pay us every month.他们每月给我们报酬。
(5)pay money back 还钱。例：May I borrow 12 yuan from you? I'll pay it back next week.你能借给我12块钱吗？下周还你。
(6)pay off one's money 还清钱。