I asked him if he had his leg broken when playing football last week.该句when引导的时间状语

题目

I asked him if he had his leg broken when playing football last week.该句when引导的时间状语
从句在变成间接引语的时候为什么时态不变,并且last week也没有变成 the week before?

答案

因为这是独立主格结构,不是从句,而且只有宾语从句才需要根据主句时态调整,其他从句没有这限制.
when playing football last week.=
when （he was）playing football last week.