---Mark broke his leg when he was playing football.

问题描述:

---Mark broke his leg when he was playing football.
---_____was that?
A.since when B.since when ago C.how long ago
C.

1AB的用法不对,since when 本身就是语法错误了,不可以用2how long ago was that那是多久以前了?i wonder how long ago this school was built我想知道这学校多久以前建造的?加个age就是表示强调多久以前做什么事因为...