He can draw well在四岁时
问题描述：
He can draw well在四岁时
答
at the age of four
答
He can draw well【when he was four】.
答
at the age of 4
when he was 4 都可以的
at the age of ...在.岁的时候
when he was ... 在他 .岁的时候 （过去时）