English verb conjugation SHOULD HAPPEN

Regular verb: happen - happened - happened


Affirmation

Simple form

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it should happen
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V-ing form

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it should be happening
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Perfect

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it should have happened
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V-ing perfect

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it should have been happening
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Negation

Simple form

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it should not happen
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V-ing form

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it should not be happening
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Perfect

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it should not have happened
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V-ing perfect

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it should not have been happening
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Interrogative form

Simple form

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should it happen?
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V-ing form

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should it be happening?
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Perfect

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should it have happened?
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V-ing perfect

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should it have been happening?
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Interro-negative form

Simple form

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should it not happen?
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V-ing form

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should it not be happening?
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Perfect

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should it not have happened?
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V-ing perfect

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should it not have been happening?
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