could checkmate
Regular verb: checkmate - checkmated- checkmated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could checkmate
you could checkmate
she could checkmate
we could checkmate
you could checkmate
they could checkmate 	I could be checkmating
you could be checkmating
she could be checkmating
we could be checkmating
you could be checkmating
they could be checkmating	I could have checkmated
you could have checkmated
she could have checkmated
we could have checkmated
you could have checkmated
they could have checkmated	I could have been checkmating
you could have been checkmating
she could have been checkmating
we could have been checkmating
you could have been checkmating
they could have been checkmating	

Negation 	
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I couldn't checkmate
you couldn't checkmate
she couldn't checkmate
we couldn't checkmate
you couldn't checkmate
they couldn't checkmate 	I couldn't be checkmating
you couldn't be checkmating
she couldn't be checkmating
we couldn't be checkmating
you couldn't be checkmating
they couldn't be checkmating	I couldn't have checkmated
you couldn't have checkmated
she couldn't have checkmated
we couldn't have checkmated
you couldn't have checkmated
they couldn't have checkmated	I couldn't have been checkmating
you couldn't have been checkmating
she couldn't have been checkmating
we couldn't have been checkmating
you couldn't have been checkmating
they couldn't have been checkmating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I checkmate?
could you checkmate?
could she checkmate?
could we checkmate?
could you checkmate?
could they checkmate? 	could I be checkmating?
could you be checkmating?
could she be checkmating?
could we be checkmating?
could you be checkmating?
could they be checkmating? 	could I have checkmated?
could you have checkmated?
could she have checkmated?
could we have checkmated?
could you have checkmated?
could they have checkmated? 	could I have been checkmating?
could you have been checkmating?
could she have been checkmating?
could we have been checkmating?
could you have been checkmating?
could they have been checkmating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I checkmate?
couldn't you checkmate?
couldn't she checkmate?
couldn't we checkmate?
couldn't you checkmate?
couldn't they checkmate? 	couldn't I be checkmating?
couldn't you be checkmating?
couldn't she be checkmating?
couldn't we be checkmating?
couldn't you be checkmating?
couldn't they be checkmating? 	couldn't I have checkmated?
couldn't you have checkmated?
couldn't she have checkmated?
couldn't we have checkmated?
couldn't you have checkmated?
couldn't they have checkmated? 	couldn't I have been checkmating?
couldn't you have been checkmating?
couldn't she have been checkmating?
couldn't we have been checkmating?
couldn't you have been checkmating?
couldn't they have been checkmating?