could caution
Regular verb: caution - cautioned- cautioned

Affirmation 	
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I could caution
you could caution
she could caution
we could caution
you could caution
they could caution 	I could be cautioning
you could be cautioning
she could be cautioning
we could be cautioning
you could be cautioning
they could be cautioning	I could have cautioned
you could have cautioned
she could have cautioned
we could have cautioned
you could have cautioned
they could have cautioned	I could have been cautioning
you could have been cautioning
she could have been cautioning
we could have been cautioning
you could have been cautioning
they could have been cautioning	

Negation 	
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I could not caution
you could not caution
she could not caution
we could not caution
you could not caution
they could not caution 	I could not be cautioning
you could not be cautioning
she could not be cautioning
we could not be cautioning
you could not be cautioning
they could not be cautioning	I could not have cautioned
you could not have cautioned
she could not have cautioned
we could not have cautioned
you could not have cautioned
they could not have cautioned	I could not have been cautioning
you could not have been cautioning
she could not have been cautioning
we could not have been cautioning
you could not have been cautioning
they could not have been cautioning	

Interrogative form 	
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could I caution?
could you caution?
could she caution?
could we caution?
could you caution?
could they caution? 	could I be cautioning?
could you be cautioning?
could she be cautioning?
could we be cautioning?
could you be cautioning?
could they be cautioning? 	could I have cautioned?
could you have cautioned?
could she have cautioned?
could we have cautioned?
could you have cautioned?
could they have cautioned? 	could I have been cautioning?
could you have been cautioning?
could she have been cautioning?
could we have been cautioning?
could you have been cautioning?
could they have been cautioning? 	

Interro-negative form 	
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could I not caution?
could you not caution?
could she not caution?
could we not caution?
could you not caution?
could they not caution? 	could I not be cautioning?
could you not be cautioning?
could she not be cautioning?
could we not be cautioning?
could you not be cautioning?
could they not be cautioning? 	could I not have cautioned?
could you not have cautioned?
could she not have cautioned?
could we not have cautioned?
could you not have cautioned?
could they not have cautioned? 	could I not have been cautioning?
could you not have been cautioning?
could she not have been cautioning?
could we not have been cautioning?
could you not have been cautioning?
could they not have been cautioning?