When does the train leave?I want to know.改为含宾语从句的复合句

问题描述:

When does the train leave?I want to know.改为含宾语从句的复合句

I want to know when the train leaves.
宾语从句要用陈述句,不用倒装.助动词 do,does did要去掉,动词还原;be动词,情态动词要放在主语后.