为什么反义疑问句let us..will you?而let`s.shall we?

为什么Let's的反义疑问句用shall we,而Let us的反义疑问句用will you 反意疑问句中为什么是Let's,shall we/Let us, will you? 请问Let us 用什么来提问反义疑问句?是Shall we 还是 will you 反义疑问句中let后怎么确定是shall we 还是will you还是别的 let's 反问用shall we ,let us 用will you let's和let us哪个用will you哪个用shall we? let's have a rest,shall we?和 let us have a rest,will you? Let’s go to school,shall we?为什么这样改反义疑问句? 英语：let’s .反义疑问句,能用shall we 肯定祈使句的反义疑问句是什么啊? let's的反意疑问句是will you还是shall we? Let us go home,_____?A.shall we B.shall us C.will you D.will Let us go swimming shall we go swimming 变成反义疑问句