We won't leave until they arrive .这里一定要用arrive为什么?
问题描述：
We won't leave until they arrive .这里一定要用arrive为什么?
答
这句话有个语法：在含有时间状语从句和条件状语从句的复合句中,如果主句用一般将来时,从句用一般现在时．eg.If it doesn't rain tomorrow,we will go.(条件状语从句)We won't leave until they arrive.(时间状语从句...