be supposed to do的否定为什么?

be supposed to do的否定为什么?
be supposed to do的否定为什么?

be supposed to do的否定为什么?
sb.be supposed to do sth.
sb.be supposed not to do sth.

be not suppose to do .suppose引导宾语从句才否定前移.这里没引导宾语从句.

be supposed not to do sth.