stand up反义疑问句后面跟什么 是will you?还是won't you?为什么?

是的,祈使句的反意疑问句,一般用will you?
祈使句后一般加上will you或won't you构成反意疑问句,用will you 多表示“请求”,用won't you 多表示提醒对方注意.例如：
Look at the blackboard,will you/ won't you?看黑板,好吗?
Let引导的祈使句有两种情况：
1)Let's...,后的反意疑问句用shall we或shan't we.例如：
Let's go home,shall we/ shan't we?回家吧,好吗?
还可以用may I来表示征求对方的同意或许可.
2)Let us/me...后的反意疑问句用will you或won't you.例如：
Let me have a try,will you/won't you?让我试一试,行吗?

will you,祈使句用will you

won't you 因为前边是一个肯定性祈使句，遵循反义疑问句 “前肯后否”原则