They must be back by 10:00p.m.at night(改为一般疑问句)

问题描述:

They must be back by 10:00p.m.at night(改为一般疑问句)
( ) ( )( )( )by10:00p.m.at night?

正确答案:Must they be back by10:00p.m.at night?
解析:有情态动词就提前情态动词,因为主语是第三人称,所以主语不用变.这样讲明白吗?