Welcome to your B1 English lesson on making deductions! Deductions are a super useful skill in English, especially for everyday conversations. When you make a deduction, you’re like a detective! You use clues and information to figure out something that isn’t directly stated. This lesson will help you understand and practice making deductions in English so you can sound more confident and natural when you speak.

What are Deductions?

Simply put, deductions are logical conclusions. Imagine you see someone wearing a doctor’s coat. You might deduce (conclude) that they work in a hospital or are a doctor. You haven’t been told directly, but based on the evidence (the doctor’s coat), you make a logical guess. In English grammar, we use specific words, especially modal verbs, to express these deductions.

Understanding how to make deductions is important for improving your spoken English. It allows you to:

• Understand implied meanings in conversations.
• Express your opinions and guesses more accurately.
• Sound more fluent and natural when speaking English.

How to Make Deductions in English

To make deductions in English, you usually follow these steps:

1. Observe the evidence: What information do you have? This could be something you see, hear, or know.
2. Use logic: Think about what this evidence suggests. What is the most likely explanation?
3. Express your deduction: Use appropriate modal verbs to show your level of certainty.

Let’s look at the key modal verbs we use for making deductions.

Modal Verbs for Deduction: Must, Might, Could, May, Can’t

Modal verbs are essential for expressing deductions. They help us show how sure we are about our conclusions. The main modal verbs for deduction are must, might, could, may, and can’t. Let’s explore each one:

Must: For Certainty (Positive)

We use ‘must’ when we are almost 100% sure about something. We have strong evidence to support our deduction.

Structure: Subject + must + be + (complement)

Examples:

• “She speaks fluent Japanese and works in Tokyo. She must be very good at her job.” (Strong evidence: fluent Japanese, working in Tokyo)
• “John didn’t sleep all night and he has dark circles under his eyes. He must be really tired.” (Strong evidence: didn’t sleep, dark circles)
• “This cake is delicious! You must be a great baker.” (Strong evidence: delicious cake)

‘Must have + past participle’ is used for deductions about the past.

Examples:

• “The door is locked and the lights are off. They must have gone out.” (Strong evidence: locked door, lights off)
• “He got 100% on the test. He must have studied really hard.” (Strong evidence: perfect score)

Might, Could, May: For Possibility (Less Certain)

We use ‘might,’ ‘could,’ and ‘may’ when we think something is possible, but we are not certain. There is some evidence, but it’s not as strong as with ‘must’. ‘Might,’ ‘could,’ and ‘may’ are often interchangeable in this context.

Structure: Subject + might/could/may + be + (complement)

Examples:

• “I haven’t seen Sarah today. She might be at home sick.” (Possible explanation, but not certain)
• “The traffic is really bad. We could be late for the meeting.” (Possible consequence of bad traffic)
• “It’s cloudy. It may rain later.” (Possible weather condition)

‘Might/Could/May have + past participle’ is used for deductions about the past (possibility).

Examples:

• “I can’t find my keys. I might have left them at the office.” (Possible past action)
• “She didn’t answer her phone. She could have been busy.” (Possible reason for not answering)
• “They didn’t come to the party. They may have forgotten about it.” (Possible reason for absence)

Can’t: For Certainty (Negative)

We use ‘can’t’ (cannot) when we are almost 100% sure that something is impossible or not true. We have strong evidence that contradicts something.

Structure: Subject + can’t + be + (complement)

Examples:

• “He doesn’t speak Spanish. He can’t be from Spain.” (Strong evidence: doesn’t speak Spanish)
• “That car is very old and broken. It can’t be very expensive.” (Strong evidence: old and broken)
• “She is a vegetarian. She can’t be eating meat.” (Strong evidence: vegetarian)

‘Can’t have + past participle’ is used for negative deductions about the past (certainty).

Examples:

• “I saw him this morning at home. He can’t have gone to work yet.” (Strong evidence: saw him at home recently)
• “She knows everything about this city. She can’t have been here for the first time.” (Strong evidence: detailed knowledge)

Let’s Practice Making Deductions!

Now it’s your turn to practice! Read each situation and complete the sentence with the correct modal verb (must, might, could, may, can’t) and the verb ‘be’ or ‘have + past participle’.

1. The lights are on at their house, and I can hear music. They _________ (be) at home.
2. She is yawning a lot and rubbing her eyes. She _________ (be) sleepy.
3. He failed the exam even though he said he studied. He _________ (study) enough. (Negative deduction)
4. I saw a woman who looked exactly like your sister. That _________ (be) her, but I’m not sure.
5. They have been together for 20 years and are very happy. They _________ (be) a very strong couple.
6. The restaurant is always empty. The food _________ (be) very good. (Negative deduction)
7. She is wearing a beautiful diamond ring. It _________ (be) very expensive.
8. He missed his flight yesterday. He _________ (arrive) on time for today’s meeting. (Negative deduction – past)
9. I haven’t seen my wallet anywhere. I _________ (leave) it at the coffee shop.
10. They are laughing and smiling. They _________ (have) a good time.

Answers to Practice

1. The lights are on at their house, and I can hear music. They must be at home.
2. She is yawning a lot and rubbing her eyes. She must be sleepy.
3. He failed the exam even though he said he studied. He can’t have studied enough. (Negative deduction)
4. I saw a woman who looked exactly like your sister. That might/could/may be her, but I’m not sure.
5. They have been together for 20 years and are very happy. They must be a very strong couple.
6. The restaurant is always empty. The food can’t be very good. (Negative deduction)
7. She is wearing a beautiful diamond ring. It must be very expensive.
8. He missed his flight yesterday. He can’t have arrived on time for today’s meeting. (Negative deduction – past)
9. I haven’t seen my wallet anywhere. I might/could/may have left it at the coffee shop.
10. They are laughing and smiling. They must be having a good time.

Improve Your Spoken English with Deductions

Congratulations on completing this lesson on making deductions in English! Practicing deductions will significantly improve your understanding and fluency in English conversations. Try to notice situations around you and practice making deductions using must, might, could, may, and can’t. The more you practice, the more natural it will become!

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Keep learning and keep practicing! You’re doing great!