when和once的区别___ you begin,I think you must continue.A.When B.Whenever C.Once D.Even if 这道题我选的是A,A也可以解释得通,如果你开始了,我认为你必须坚持.可答案是C,为什么?

when和once的区别___ you begin,I think you must continue.A.When B.Whenever C.Once D.Even if 这道题我选的是A,A也可以解释得通,如果你开始了,我认为你必须坚持.可答案是C,为什么? once 与when的区别 例句 once again和once more的区别? when will you 和when you will的区别 is this flat ___ you once lived in为什么填the one?和 Is this the flat which/ that you once lived in 有什么区别? when与while,since和once得区别 once to be seen 和once being seen的区别 one和ones和once的区别 At once和at first的区别 right now 和 at once 的区别? When did you go there?和 When did you went there?的区别 Please write to me at once when you arrive .(同义句)Please write to me at once when you arrive .(改为同义句)Please write to me ___ ___ ____ you arrive. when do you和when are you 有什么区别? 翻译：你何时开始学英语的?When ___ you ___ ___ English? once more,one more time和once again有什么区别once moreone more timeonce again都是再一次的意思? While和When的区别? when和while的区别 when和while的区别