在英语中情态动词是一些特殊的动词，它们不能单独使用，必须跟随一个主要动词来辅助表达。

情态动词在英语中用来表达能力、可能性、许可、义务等多种情感和语气。

Can & Could

Can 表达能力或许可

• 能力：Sha can swim very fast.
• 许可：Can I leave early today?

Could 表示一种更礼貌的请求或表达可能性（Can 的过去式）

• 过去的能力：When I was younger, I could run faster.
• 礼貌请求：Could you help me with this?

May & Might

May 用来表达可能性或许可

• 可能性：It may rain later.
• 许可：May I use your phone?

Might 表示更不确定的可能性（May 的过去式）

• 不确定的可能性：She might come to the party.

Will & Would

Will 表达未来或自愿做某事

• 未来：I will go to the meeting tomorrow.
• 意愿：I will help you with your homework.

Would 表示条件、请求或假设（Will 的过去式）

• 条件：If I were you, I would study harder.
• 请求：Would you like some coffee?
• 假设：She would visit if she had time.

Shall & Should

Shall 用于第一人称，用来提出建议或表示未来的行为

• 建议：Shall we go for a walk?
• 未来事件：I shall return tomorrow.

Should 用于建议或表示责任和义务（Shall 的过去式）

• 建议：You should see a doctor.
• 义务：Students should respect their teachers.

Must

Must 表达强制性或高度的可能性

• 强制性：You must wear a seatbelt while driving.
• 高度可能性：She must be at home, the lights are on.

注意事项

• 情态动词后的主要动词使用原形形式，即使主语是第三人称