a  What do you want to buy him?你想要给他买什么？

 I want to buy him a tie.我想给他买一条领带。

b  What do you want to buy her?你想给她买什么？

 I want to buy her a new bike.我想给她买一辆新自行车。

c  What do you want to buy them?你想给他们买什么？

 I want to buy them shoes.我想给他们买鞋。

d  What do you want to buy me?你想给我买什么？

 I want to buy you a bag.我想给你买一个书包。