他23岁时当了老师.是He was a teacher when he was 23还是he became a teacher when he was 23.为什么?

问题描述:

他23岁时当了老师.是He was a teacher when he was 23还是he became a teacher when he was 23.为什么?

was强调状态,became强调动作=_=所以成了用became