would happen
Regular verb: happen - happened- happened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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it'd happen
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it'd be happening
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it would've happened
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it would've been happening
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Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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it wouldn't happen
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it wouldn't be happening
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it wouldn't have happened
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it wouldn't have been happening
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Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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would it happen?
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would it be happening?
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would it have happened?
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would it have been happening?
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Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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wouldn't it happen?
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wouldn't it be happening?
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wouldn't it have happened?
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wouldn't it have been happening?
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