When he was in his fifties Marx began to learn English.

题目

When he was in his fifties Marx began to learn English.
我想问的是 为什么 WHEN HE 后面跟的是WAS 而不是IS?这个叫什么从句?
是不是后面从句用什么时态,前面主句就要用同样的时态?

答案

前面是时间状语从句.后面才是主句.从句时态要与主句一致.