be supposed to:表示“按规定/按约定应该……;被期望……;(有时也表示)据说/被认为……”。常用于表达义务、期待或传闻。(也可根据语境带有“本该却没做到”的含义。)
/bi səˈpoʊzd tuː/
You’re supposed to wear a helmet when you ride a bike.
你骑自行车时应该戴头盔。
The report was supposed to be finished by Friday, but the team ran into unexpected problems.
报告本应在周五前完成,但团队遇到了意外问题。
suppose 来自拉丁语 supponere(意为“放在下面、假定”),经由法语进入英语。be supposed to 由“被假定/被认为”发展出“按约定应当、被期待要做”的固定用法;在口语中也常引申为“据说”。