supposed
be supposed to 的用法
用法一：be supposed to...其中to是動詞不定式符號,不是介詞,其后要跟動詞原形.當be supposed to...的主語是“人” 時,意為“應該……”；“被期望……”,它可以用來表示勸告、建議、義務、責任等,相當于情態(tài)動詞should.如：
Everyone is supposed to wear a seat-belt in the car.
用法二：當be supposed to...的主語是“物”時,它表示“本應；本該”,用于表示“某事本應該發(fā)生而沒有發(fā)生”.如：
The new laws are supposed to prevent crime.這些新法令本應該起到防止犯罪的作用.
用法三：be supposed to后面接“have + 過去分詞”時,表示“本應該做某事而沒做”.如：
You are supposed to have handed in your homework by now.
現在你應該已經把作業(yè)交上來了.
He is supposed to have arrived an hour ago.他應該一小時前就到了.
用法四：be supposed to...的否定結構為be not supposed
to...,它常用于口語中,意為“不被許可；不應當”.如：
She was not supposed to be angry about that.她本不該為那件事而生氣的.
You are not supposed to smoke on the bus.你不應該在公共汽車上吸煙.