could shutter
Regular verb: shutter - shuttered- shuttered

Affirmation 	
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I could shutter
you could shutter
she could shutter
we could shutter
you could shutter
they could shutter 	I could be shuttering
you could be shuttering
she could be shuttering
we could be shuttering
you could be shuttering
they could be shuttering	I could have shuttered
you could have shuttered
she could have shuttered
we could have shuttered
you could have shuttered
they could have shuttered	I could have been shuttering
you could have been shuttering
she could have been shuttering
we could have been shuttering
you could have been shuttering
they could have been shuttering	

Negation 	
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I couldn't shutter
you couldn't shutter
she couldn't shutter
we couldn't shutter
you couldn't shutter
they couldn't shutter 	I couldn't be shuttering
you couldn't be shuttering
she couldn't be shuttering
we couldn't be shuttering
you couldn't be shuttering
they couldn't be shuttering	I couldn't have shuttered
you couldn't have shuttered
she couldn't have shuttered
we couldn't have shuttered
you couldn't have shuttered
they couldn't have shuttered	I couldn't have been shuttering
you couldn't have been shuttering
she couldn't have been shuttering
we couldn't have been shuttering
you couldn't have been shuttering
they couldn't have been shuttering	

Interrogative form 	
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could I shutter?
could you shutter?
could she shutter?
could we shutter?
could you shutter?
could they shutter? 	could I be shuttering?
could you be shuttering?
could she be shuttering?
could we be shuttering?
could you be shuttering?
could they be shuttering? 	could I have shuttered?
could you have shuttered?
could she have shuttered?
could we have shuttered?
could you have shuttered?
could they have shuttered? 	could I have been shuttering?
could you have been shuttering?
could she have been shuttering?
could we have been shuttering?
could you have been shuttering?
could they have been shuttering? 	

Interro-negative form 	
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couldn't I shutter?
couldn't you shutter?
couldn't she shutter?
couldn't we shutter?
couldn't you shutter?
couldn't they shutter? 	couldn't I be shuttering?
couldn't you be shuttering?
couldn't she be shuttering?
couldn't we be shuttering?
couldn't you be shuttering?
couldn't they be shuttering? 	couldn't I have shuttered?
couldn't you have shuttered?
couldn't she have shuttered?
couldn't we have shuttered?
couldn't you have shuttered?
couldn't they have shuttered? 	couldn't I have been shuttering?
couldn't you have been shuttering?
couldn't she have been shuttering?
couldn't we have been shuttering?
couldn't you have been shuttering?
couldn't they have been shuttering?