——Mom,shall we have supper now?

——Mom,shall we have supper now?
——Oh,we won't have supper _______ your dad comes back.
我知道应该填until,但是我想问一下,填unless不行吗?如果选项里同时有until和unless,应该选哪个呢?他们俩的区别是什么呢?

not...until 直到 这里强调的是时间,爸爸回来后才吃饭.两个词的区别主要如下：
一、作为从属连词含义不同,引导从句性质不同
　　unless与until均为从属连词,unless表"除非",强调条件,引导条件状语从句;until表"直到",强调时间的延续,引导时间状语从句.
　　1.I didn't know the news until my teacher told it to me.
　　2.I couldn't know the news unless my teacher told it to me.
　　3.-Was his father very strict with him when he was at school?
　　-Yes.He had never praised him until he became one of the top students in his grade.
　　析:句1动词didn't know表明该句强调时间的延续,表"我不知道这消息"的状态一直延续到"老师告诉我",因此应用until引导时间状语从句.句2动词couldn't know表明该句强调条件,表"我不可能知道这消息,除非老师告诉我",因此应用unless引导条件状语从句.句3表明"他爸爸从来没有表扬他"的状态一直延续到"他变成年级最好的学生之一",因此也应用until引导时间状语从句.
　　二、作为从属连词引导的从句常用一般现在时表示将来
　　unless引导的条件状语从句和until引导的时间状语从句常用一般现在时表示将来.
　　例1:除非邀请你否则别进来.
　　误:Don't come in unless you will be invited to.
　　正:Don't come in unless you're invited to.
　　例2:除非他来,我们不可能去.
　　误:Unless he will come,we won't be able to go.
　　正:Unless he comes,we won't be able to go.
　　三、作为从属连词引导的状语从句可转换为省略式创新句型
　　unless引导条件状语从句和until引导时间状语从句时,如果主从句主语一致(或主从句主语不一致,但从句主语为it),从句谓语部分含有be,可将从句主语和动词be省略,构成省略式创新句型.
　　例1:I won't come to see you unless I am asked to.除非你邀请我,我才会来看你.
　　析:因为主从句主语一致,从句谓语又含有am,所以可将从句主语I和动词am 省略,构成省略式创新句型:I won't come to see you unless asked to.
　　例2:The soldiers will not cross the river unless they are ordered to.除非接到命令,战士们不会过河.
　　析:因为主从句主语一致,从句谓语又含有are,所以可将从句主语they和动词are省略,构成省略式创新句型:The soldiers will not cross the river unless ordered to.
　　注意:
　　until也可作为介词.例如:
　　I have remembered her until now.直到现在我还记得她.