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GZ12.06 - Deduction

Choose a grammar card

A - Must - Strong Positive Deduction

B - Might - Possible Deduction

C - May - Possible Deduction

D - Could - Possible Deduction

E - Can't - Strong Negative Deduction

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GZ12.06A - Must - Strong Positive Deduction

[P] = Person/subject

Use must when the evidence makes you almost certain something is true.

[P] + must be + description + because + reason

Jack must be tired because he worked all night.

This must expresses a logical conclusion, not a rule or obligation. The reason gives evidence for your conclusion. Must be is followed by an adjective, noun or location.

✓ Jack must be tired because he worked all night.

✗ Jack must to be tired.

✗ Jack must is tired.

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GZ12.06B - Might - Possible Deduction

[P] = Person/subject

Use might when the evidence suggests something is possible, but you are not sure.

[P] + might be + description + because + reason

Anna might be at work because her car isn't here.

Might shows uncertainty. The evidence supports one possible explanation, but there may be others. Use the base verb be after might.

✓ Anna might be at work because her car isn't here.

✗ Anna might is at work.

✗ Anna might to be at work.

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GZ12.06C - May - Possible Deduction

[P] = Person/subject

Use may to suggest a possible explanation based on what you know.

[P] + may be + description + because + reason

Anna may be at work because her car isn't here.

May expresses uncertainty, much like might. It can sound slightly more formal. The evidence does not prove the conclusion.

✓ Anna may be at work because her car isn't here.

✗ Anna may is at work.

✗ Anna may to be at work.

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GZ12.06D - Could - Possible Deduction

[P] = Person/subject

Use could to offer one possible explanation of the evidence.

[P] + could be + description + because + reason

Anna could be at work because her car isn't here.

Could here does not describe past ability. It means the conclusion is possible, not certain. Another explanation may also fit.

✓ Anna could be at work because her car isn't here.

✗ Anna could is at work.

✗ Anna could to be at work.

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GZ12.06E - Can't - Strong Negative Deduction

[P] = Person/subject

Use can’t when the evidence makes you almost certain something is not true.

[P] + can't be + description + because + reason

That can't be John because he's in London.

Can't expresses a strong negative conclusion, not inability here. The evidence makes the proposed explanation seem impossible.

✓ That can't be John because he's in London.

✗ That can't is John.

✗ That can't to be John.

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