关键在于suppose的用法.
1.suppose sb to do sth.及其被动语态 be supposed to do sth.
2.suppose sb be doing sth及其被动语态 be supposed to be doing
不存在be supposed 后面直接加doing的用法,因为不符合被动语态语法.
例句:No one was supposed to tee us laughing.此处的laughing 是动名词用法,而不是所谓的be supposed doing .