What about staying here till Tuesday, and leave for Mianyang on Wednesday?错在哪？？

leaving
what about doing and doing...

What about staying here till Tuesday, and [[[leaving]]] for Mianyang on Wednesday?

你要看 and 连接的部分，这里都是连接 what about 后面的部分，
连接部分都作about的宾语，既然是介词的宾语，所以，当然用动词ing形式

答案 leaving，和前面的staying一致

leave改为leaving,
与staying并列做about的宾语

leave 改称 leaving
因为what about后用and连接了两个并列的谓语,它们的形式必须一致
what about后接v-ing

leave 改称 leaving