we have two room__,but I can't decide___

问题描述:

we have two room__,but I can't decide___
Ato live ,to choose which one
Bto live in ,which one to choose
怎样区别什么时候加介词,什么时候不加
分析下从句

选择B.如果动词前有名词,则需要加上介词,第一个空,live 前有名词room ,所以要加上介词in,choose前没有名词,所以不加介词