3道英语选择题,求详解

题目

3道英语选择题,求详解
麻烦详细解释一下～～谢谢!
（ ）hearing the bad news, she immediately went home.
A: at B:on C:while
( ) he once went bankrupt, he thought of ending his life.
A:whenever B:as C:when
he let the artist ( ）picture of him.
A:to paint B:paint C: painted

答案

1（ ）hearing the bad news,she immediately went home.A:at B:on C:while这一题选择B on doing sth 表示的是“一……就” 这句话的意思是：一听到这个坏消息,她立马回家了.拓展：On seeing his dad,the baby cries...