by doing; in doing ;on doing 的意思

by doing;通过做......
in doing 在......做
on doing 依靠,根据做.....
其实应该根据前句的动词而决定的.

by doing通过做
in doing在做...时
on doing一做...就...

by doing 表示方式
in doing 表示状态
on doing 表示依靠，依赖什么做这种状态