Modal verbs in the past differ from modal verbs in the present. Analyze this chart:
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MODAL VERBS IN THE PAST |
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Can |
Add HAVE and then add verb ending in -ed or past participle |
Can have |
When the episode happened I do not think I can have been less than fifteen years old! |
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Could |
Could have |
It could have been me! |
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May |
May have |
She may have rung! |
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Might |
Might have |
They might have read the document! |
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Should |
Should have |
I should have told you before! |
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Ought to |
Ought to have |
I ought to not have called them. |
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Will |
- |
- |
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Would |
Would have |
It wouldn’t have been much easier. |
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Must |
Must have |
You must have done it! |
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Able to |
Change into the appropriate tense
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Was able to/Had been able to |
I wasn’t able to do it. |
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Need to |
Needed to/Had needed to |
He needed to buy a new suit. |
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Have to |
Had to/Had had to |
They had to take a break. |
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