一、be supposed to do 结构深化

时态变化与含义

一般现在时（are/is supposed to）：强调当下的 “应该” 或 “被期望”，如：
You are supposed to submit the report by Friday.（你应该在周五前提交报告。）

一般过去时（were/was supposed to）：强调过去本应做却未做的事，暗含 “未完成” 的遗憾，如：
She was supposed to meet us at the station, but she didn’t show up.（她本应在车站接我们，但没来。）

否定句正确形式
需在 be 动词后加 not，即 be not supposed to，而非 “your not supposed to”（注意：主语是 “you” 时，所有格应为 “your”，但否定句结构是 “You are not supposed to...”）。例如：

You are not supposed to smoke in the library.（你不应该在图书馆抽烟。）

He is not supposed to leave the classroom without permission.（他未经允许不应该离开教室。）二、had better do 结构拓展

否定形式：had better not do（最好不要做），如：

You’d better not eat too much candy.（你最好不要吃太多糖果。）

We’d better not arrive late for the meeting.（我们最好不要开会迟到。）

造句示例

You’d better take an umbrella—it might rain.（你最好带把伞，可能会下雨。）

She’d better study harder for the final exam.（她最好为期末考试更努力学习。）

They’d better call the police about the accident.（关于这起事故，他们最好报警。）三、两者区别

结构语气特点适用场景

be supposed to偏正式，强调 “按规定 / 期望应做”规则、责任、社会规范等（如校规、工作要求）

had better偏口语，强调 “建议 / 警告”给出实用建议、提醒潜在风险（如天气、健康）

例如：

校规场景：Students are supposed to wear uniforms.（学生应该穿校服。）

临时建议：You’d better wear a warm coat—it’s cold outside.（你最好穿件厚外套，外面很冷。）

一、be supposed to do 句型及翻译

You are supposed to be here.
你应该在这里。

You're supposed to follow the rules.
你应该遵守规则。

You're supposed to obey the rules.
你应该遵守规则。

You were supposed to turn off your phone.
你本应该关掉手机的。

You're supposed to wear a mask.
你应该戴口罩的。

You're supposed to take your shoes off.
你是应该脱鞋的。

二、had better (you'd better) do 句型及翻译

You'd better check the expiration date.
你最好看一下过期日期。

You'd better be careful.
你最好小心一点。