You come back→问句 Do you come back?
你回来 → 你回来吗?(一般不会用到这句,只会说"你会回来吗?" Will you come back?)
You are coming back→ Are you coming back?
你正在回来/你会回来→你正回来吗?/ 你会回来吗?注意这里是coming 不是 come
简单来说, be动词 +-ing型式 = 进行式
其他都不用be动词.
do you come back 怕写成are you come back 的话,记住：
You come back = You do come back(一样的意思,加重语气)
→ Do you come back?