Question

My pen dropped on the ground when I was walking in the park和A woman saw it happen when she was

My pen dropped on the ground when I was walking in the park和A woman saw it happen when she was walking past.中的when 可以换成while 吗？

Answer 1

两句都可以，因为when后面的动词walk是持续性动词，可以换成while。
但如果是短暂性动词就不能用while了。

Answer 2

可以，while可以引导延续性动词的时间状语从句。walk是延续性动词