be supposed to

用法示例

1. You are supposed to be at the meeting by 9 a.m.你应该在上午9点前到会。
2. The movie is supposed to be really good.这部电影据说很好看。
3. We were supposed to go out, but it rained.我们本打算出去，但下雨了。
4. You're not supposed to smoke in here.你不可以在这里吸烟。
5. He is supposed to be an expert in ancient history.他被认为是古代史专家。
6. The new policy is supposed to take effect next month.新政策预计下个月生效。

含义详解

本义为“被期望或被要求做某事”，源自suppose的被动形式，表示“被假定”。引申出三个主要义项：1）表示义务或规定，相当于should，例如“You are supposed to wear a uniform.”（你应该穿制服）；2）表示预期或计划，指按安排应当发生，例如“The train is supposed to arrive at 6.”（火车预计6点到）；3）表示普遍看法，意为“被认为”，例如“He is supposed to be an expert.”（他被认为是专家）。此外，否定形式“be not supposed to”常表示“不允许”，语气较强。

词源解析

suppose源自拉丁语supponere，由sub-（在…之下）和ponere（放置）组成，本义为“放在下面”，后引申为“假定、认为”。be supposed to是suppose的被动结构，字面意思为“被假定为”，由此衍生出“应当”的含义。记忆时可联想：某事物被放置在某种预期之下，因此有“应该”之义。

适用语境

日常口语中极为常见，用于提醒义务或期望，如“You're supposed to call first.”。商务邮件中常用于委婉表达要求，如“You are supposed to submit the report by Friday.”。新闻报道中用于描述预期事件，如“The meeting is supposed to start at 9.”。文学作品中也常见，用于表达人物内心的预期或社会规范。语气上，口语中较随意，书面语中更正式，但整体属于中性偏正式表达。

用法须知

固定搭配，后接动词原形，结构为“be + supposed + to + 动词原形”。be动词需随主语和时态变化，如“is supposed to”、“were supposed to”。否定形式为“be not supposed to”，疑问句将be动词提前。注意：supposed不可单独作谓语，需用被动结构。常见易错点：误用为“suppose to”，漏掉be动词。

相似词辨析

与“should”和“ought to”相比，be supposed to更强调外部期望或计划，而非内在义务。例如“You should apologize.”（你应该道歉）指道德上应当，而“You are supposed to apologize.”（你理应道歉）指按照规则或期望。与“be expected to”相比，后者更正式，强调预期性。与“be meant to”相比，后者更强调目的性。

常见误区

语域中性，适用于多种场合，但正式写作中可能更偏好“be expected to”。否定形式“not supposed to”语气较强，表示禁止，需注意语境。常见误用包括：拼写为“suppose to”；忘记be动词；将“supposed”误当作形容词。

常见搭配

• be supposed to do sth.
• be supposed to be
• be not supposed to
• be supposed to have done
• be supposed to be doing
• be widely supposed to
• be generally supposed to