Series ID: EDKS-BASIC-ZH-0058 · Lesson No.058 · B1-Direction Possibility and Deduction
Modals of Possibility and Deduction | 可能性与推断
She might be at home. He must be tired. That can’t be the right train.
她可能在家。他一定很累。那不可能是正确的火车。
B1-direction English needs calibrated certainty. Sometimes you know. Sometimes you think something is likely. Sometimes you only see evidence and make a deduction.
这一课训练的是“把确定程度说准确”：不要把“可能”说成“肯定”，也不要把有证据的强推断说得过分模糊。
Chinese Edition Hub · 中文版入口 · ← Lesson No.057 · Past Perfect for Earlier Past
The certainty map | 确定程度路线
- may / might / could
- probably / maybe / perhaps
- must for strong deduction
- can’t for strong negative deduction
- couldn’t be
- evidence language
- present deduction
- past deduction recognition
- possibility vs permission
- Mandarin 可能/一定/不可能 transfer
1. Possibility | 可能性
- She may be at home.
- She might be at home.
- She could be at home.
All can express possibility in many contexts.
2. May | may
- It may rain later.
- The meeting may finish early.
3. Might | might
- He might be busy.
- We might take the later train.
might often sounds slightly less certain, though real usage overlaps.
4. Could | could
- The problem could be the cable.
- She could still be at work.
Here could means possible, not past ability.
5. Maybe / perhaps | 也许
- Maybe she’s at home.
- Perhaps the train is delayed.
These are adverbs, not modal verbs.
6. Probably | 很可能
- She’s probably at home.
- It will probably rain later.
7. Strong deduction with must | 强推断
must can mean strong logical deduction:
- You’ve been working all day. You must be tired.
- The lights are off and the door is locked. They must be out.
8. This is not obligation must | 不是“必须”的 must
- You must wear ID. → obligation
- You must be tired. → deduction
Context changes function.
9. Strong negative deduction with can’t | 强否定推断
- That can’t be Anna; she’s abroad.
- This can’t be the right room; the sign says Room 5.
10. Can’t ≠ don’t know | can’t 不是“不确定”
can’t expresses strong belief that something is impossible or almost impossible.
11. Evidence → deduction | 证据→推断
Evidence:
The ground is wet.
Possible deduction:
- It might have rained. — past deduction recognition
- Someone may have washed the floor.
12. Present deduction | 现在推断
- She must be busy.
- He might be asleep.
- They can’t be at home.
13. Modal + be | modal + be
- might be
- must be
- can’t be
14. Modal + base verb | modal + 动词原形
- She may know.
- He might come.
- They could arrive early.
15. No -s after modal | modal 后动词不加 -s
- She might knows. ✗
- She might know. ✓
16. No to after basic modal | modal 后不用 to
- He may to come. ✗
- He may come. ✓
17. Negative possibility | 否定可能
- She may not know.
- He might not come.
This means “possibly not”, not strong impossibility.
18. May not vs can’t | may not vs can’t
- She may not be home. → possibly not home
- She can’t be home. → strong deduction she is not home
19. Could be vs must be | could be vs must be
- It could be a software problem. → one possible explanation
- It must be a software problem. → strong deduction
20. Evidence strength matters | 证据强度决定语言
One weak clue should not usually produce a strong must.
21. Epistemic humility | 推断要克制
If evidence is incomplete, use possibility language rather than certainty.
22. “I think” + modal | I think + modal
- I think she might be at work.
- I think it could be the battery.
This can soften the claim further.
23. “It looks like…” | 看起来像……
- It looks like the shop may be closed.
24. “It sounds like…” | 听起来像……
- It sounds like the train might be delayed.
25. “Based on…” | 根据……
- Based on the message, the meeting may have been moved. — recognition
26. Possibility in plans | 计划中的可能
- We might go out later.
- I may work from home tomorrow.
27. Possibility in problem solving | 问题解决
- The issue could be the password.
- The file might be damaged.
28. Possibility in travel | 出行
- The platform may change.
- The bus might be late.
29. Possibility in weather | 天气
- It may rain.
- There could be thunderstorms later.
For real weather decisions, use official forecasts rather than learner guesses.
30. Deduction from behaviour | 根据行为推断
- She hasn’t replied all day. She might be busy.
Do not turn ordinary uncertainty into invasive personal assumptions.
31. Deduction from visible evidence | 根据可见证据
- The screen is black. The device might be off.
- The cable is disconnected. That could be the problem.
32. Strong deduction needs stronger evidence | 强推断需要强证据
The door is locked, the lights are off, and nobody answers. They must be out.
33. Past deduction recognition | 过去推断认识
B1 learners will meet:
- must have + past participle
- might have + past participle
- can’t have + past participle
34. Must have + participle | 对过去的强推断
- He must have forgotten the meeting.
Strong deduction about a past event.
35. Might have + participle | 对过去的可能推断
- She might have taken the earlier train.
36. Can’t have + participle | 对过去的强否定推断
- He can’t have sent the file; his computer was offline.
Recognition and careful use only; evidence still matters.
37. Present vs past deduction | 现在 vs 过去推断
- He must be tired. → now
- He must have been tired. → past
38. Could for possibility vs ability | could 多种功能
- She could swim at five. → past ability
- She could be at the pool now. → possibility
39. May for possibility vs permission | may 多种功能
- It may rain. → possibility
- You may leave now. → permission, formal
40. Must for deduction vs obligation | must 多种功能
- You must leave now. → obligation
- You must be tired. → deduction
41. Mandarin transfer: 可能 | may/might/could
Chinese 可能 can map to several English expressions depending on certainty and sentence structure.
42. Mandarin transfer: 一定 | must / definitely / probably
Do not always translate 一定 as must. If it is a logical deduction, must may fit. If it is a prediction or emphasis, another form may be better.
43. Mandarin transfer: 不可能 | can’t / impossible
- 那不可能是他。 → That can’t be him.
44. Reading practice A | 阅读 A
Anna’s office is dark and the door is locked. Her coat is gone, and she isn’t answering her desk phone. She must have left for the day, although she might still be somewhere else in the building.
- Which deduction is stronger?
- Which possibility is weaker?
- What evidence supports each?
45. Reading practice B | 阅读 B
David can’t find his keys. They could be in his jacket, or he might have left them at the café. They can’t be in the car because the car is locked and he used the keys to enter the house.
- Name two possibilities.
- What does David rule out?
- What evidence supports the negative deduction?
46. Speaking practice: evidence ladder | 证据阶梯
Teacher gives evidence. Learner chooses:
- may/might/could
- must
- can’t
Then explain why.
47. Writing practice: three confidence levels | 三个确定程度
For one scenario, write:
- one weak possibility
- one strong deduction
- one ruled-out possibility
48. Error clinic | 常见错误
| Error | Better English |
|---|---|
| She might knows. ✗ | She might know. ✓ |
| He may to be late. ✗ | He may be late. ✓ |
| She must not be home. △ | She can’t be home. ✓ for strong negative deduction |
| It maybe is broken. △ | Maybe it’s broken. / It may be broken. ✓ |
49. First weak link diagnosis | 第一个卡点诊断
- I use one modal for everything → certainty scale problem.
- I confuse obligation and deduction → function/context problem.
- I use can’t for weak uncertainty → confidence mismatch.
- I overclaim from weak evidence → reasoning problem.
- I know grammar but cannot justify choice → evidence-link problem.
50. Retrieval lab | 提取练习
- 她可能在家。 → ______
- 他一定很累。 → ______
- 那不可能是正确的房间。 → ______
- 问题可能是电池。 → ______
- 他可能忘了会议。 → ______
Suggested answers: She might be at home. / He must be tired. / That can’t be the right room. / The problem could be the battery. / He might have forgotten the meeting.
51. Seven-day training cycle | 七天训练
| Day 1 | may/might/could | 可能 |
| Day 2 | must/can’t | 强推断 |
| Day 3 | evidence language | 证据 |
| Day 4 | function contrasts | 多义 |
| Day 5 | past deduction recognition | 过去推断 |
| Day 6 | scenario reasoning | 情境 |
| Day 7 | five-minute evidence discussion | 综合 |
52. Self-test | 自测
Use may/might/could; use must and can’t for deduction; explain evidence; distinguish possibility from permission and obligation; recognise must/might/can’t have + participle; calibrate certainty in five scenarios.
53. For parents and teachers | 给家长和老师
Teach modals as confidence choices attached to evidence.
Ask “What evidence do you have?” after every deduction.
For Mandarin speakers, avoid one-to-one translation of 可能/一定/不可能; map function and certainty.
54. Final real-world challenge | 最终真实任务
- Express five possibilities.
- Make five strong deductions.
- Rule out three explanations.
- Explain the evidence behind each choice.
- Distinguish may/might/could.
- Distinguish must deduction from obligation.
- Recognise three past-deduction forms.
- Use deduction in a problem-solving dialogue.
- Write a short evidence-based reasoning paragraph.
- Complete a five-minute deduction discussion without overclaiming.
Next: Lesson No.059 | 下一课
The next lesson moves from grammar choice to register choice: how the same message changes across friends, teachers, colleagues, service staff, emails and formal requests.
Lesson No.059 · Formal and Informal English · 正式与非正式英语
Reference floor: British Council B1 Intermediate.
