Modal verbs — can, should, must · 情态动词 — can、should、must
Modal verbs — little helpers
- Modal verbs add meaning: ability, advice, obligation.
- can, could, should, must, have to.
- They are followed by the base verb (no to, no -s).
You should sleep; your alarm clock is ready for tomorrow.
情态动词 —— 小帮手
- 情态动词增加意思:能力、建议、义务。
- can、could、should、must、have to。
- 它们后面跟动词原形(不加 to,不加 -s)。
你应该睡觉；闹钟已经准备好明天了。
can / could — ability & requests
- can = ability or possibility: I can swim.
- could = past ability, or a polite request: She could read at four. Could you help me?
- After can / could, use the base verb: can swim (not can to swim).
can / could —— 能力与请求
- can = 能力或可能:我I 会can 游泳swim.(我会游泳。)
- could = 过去的能力,或客气的请求:She could read at four. Could you help me?
- can / could 后面用动词原形:can swim(不是 ~~can to swim~~)。
Which sentence is correct? · 哪一句正确?
A modal is followed by the base verb (no “to”, no -ing): “can swim”. · 情态动词后面跟动词原形(不加 to,不加 -ing):can swim。
should — advice
- should = advice, "it's a good idea": You should see a doctor.
- Negative shouldn't = "it's not a good idea": You shouldn't eat so late.
- It is softer and gentler than must.
should —— 建议
- should = 建议、"应该":你You 应该should 看see 一位a 医生doctor.(你应该去看医生。)
- 否定 shouldn't = "不该":You shouldn't eat so late.
- 语气比 must 委婉、温和。
Give advice: You ___ see a doctor. (use one modal verb) · 给建议:You ___ see a doctor。(用一个情态动词)
Advice → should: “You should see a doctor.” · 建议 → should:You should see a doctor。
Translate into English: 你应该去看医生。 · 翻译成英语:你应该去看医生。
Advice → should + base verb: “You should see a doctor.” · 建议 → should + 动词原形:You should see a doctor。
must / have to — obligation
- must and have to = "it's necessary": You must wear a seatbelt. I have to get up early.
- mustn't = it's forbidden: You mustn't smoke here.
- don't have to = it's not necessary: You don't have to come.
must / have to —— 义务
- must 和 have to = "必须":You must wear a seatbelt. I have to get up early.
- mustn't = 禁止:你You 禁止mustn't 吸烟smoke 这里here.(这里禁止吸烟。)
- don't have to = 不必:You don't have to come.
What does the modal do? · 这个情态动词表达什么?
can = ability; should = advice; must / have to = obligation. · can = 能力;should = 建议;must / have to = 义务。
“You mustn't smoke here.” — Does this mean it is forbidden? · “You mustn't smoke here.” —— 这是表示禁止的意思吗?
mustn't = it is forbidden. (don't have to = not necessary — different!) · mustn't = 禁止。(don't have to = 不必 —— 意思不同!)
Common mistakes
- ❌ You must to go. → ✓ You must go. — modals never take to.
- ❌ She musts study. → ✓ She must study. — modals never take -s.
- Careful: mustn't = not allowed; don't have to = not necessary. Opposite meanings!
常见错误
- ❌ You must to go. → ✓ You must go。—— 情态动词后面永远不加 to。
- ❌ She musts study. → ✓ She must study。—— 情态动词没有 -s。
- 分清:mustn't = 禁止;don't have to = 不必。意思正好相反!
Match each sentence to its meaning. · 把句子和它的含义配对。
mustn't forbids; don't have to means it's optional; should advises; must requires. · mustn't 禁止;don't have to 表示可做可不做;should 建议;must 要求。
Complete with the past of “must”: Yesterday I ___ work late. · 用 must 的过去形式填空:Yesterday I ___ work late.
must has no past form — use had to. · must 没有过去式,过去的义务用 had to。
- Modals + base verb (no to, no -s).
- can / could = ability & requests; should = advice.
- must / have to = necessary; mustn't = forbidden ≠ don't have to = not necessary.
- 情态动词 + 动词原形(不加 to,不加 -s)。
- can / could = 能力与请求;should = 建议。
- must / have to = 必须;mustn't = 禁止 ≠ don't have to = 不必。
A friend is tired and stressed. Write one sentence of advice using “should”. · 一个朋友又累又紧张。用 should 写一句建议。
Example: “You should go to bed early and relax.” · 例如:You should go to bed early and relax。