新概念第三册41

题目

新概念第三册41
They could be saved so such misery and expanse if they chose to live in the city where they rightly belong.为什么要用be saved被动语态?为什么要用过去时?我觉得他是说了一种现象

答案

本句用了与现在事实不符的虚拟语气结构.
主动语态为：To live in the city could save them so much misery and expense.