could menstruate
Regular verb: menstruate - menstruated- menstruated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could menstruate
you could menstruate
he could menstruate
we could menstruate
you could menstruate
they could menstruate 	I could be menstruating
you could be menstruating
he could be menstruating
we could be menstruating
you could be menstruating
they could be menstruating	I could have menstruated
you could have menstruated
he could have menstruated
we could have menstruated
you could have menstruated
they could have menstruated	I could have been menstruating
you could have been menstruating
he could have been menstruating
we could have been menstruating
you could have been menstruating
they could have been menstruating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't menstruate
you couldn't menstruate
he couldn't menstruate
we couldn't menstruate
you couldn't menstruate
they couldn't menstruate 	I couldn't be menstruating
you couldn't be menstruating
he couldn't be menstruating
we couldn't be menstruating
you couldn't be menstruating
they couldn't be menstruating	I couldn't have menstruated
you couldn't have menstruated
he couldn't have menstruated
we couldn't have menstruated
you couldn't have menstruated
they couldn't have menstruated	I couldn't have been menstruating
you couldn't have been menstruating
he couldn't have been menstruating
we couldn't have been menstruating
you couldn't have been menstruating
they couldn't have been menstruating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I menstruate?
could you menstruate?
could he menstruate?
could we menstruate?
could you menstruate?
could they menstruate? 	could I be menstruating?
could you be menstruating?
could he be menstruating?
could we be menstruating?
could you be menstruating?
could they be menstruating? 	could I have menstruated?
could you have menstruated?
could he have menstruated?
could we have menstruated?
could you have menstruated?
could they have menstruated? 	could I have been menstruating?
could you have been menstruating?
could he have been menstruating?
could we have been menstruating?
could you have been menstruating?
could they have been menstruating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I menstruate?
couldn't you menstruate?
couldn't he menstruate?
couldn't we menstruate?
couldn't you menstruate?
couldn't they menstruate? 	couldn't I be menstruating?
couldn't you be menstruating?
couldn't he be menstruating?
couldn't we be menstruating?
couldn't you be menstruating?
couldn't they be menstruating? 	couldn't I have menstruated?
couldn't you have menstruated?
couldn't he have menstruated?
couldn't we have menstruated?
couldn't you have menstruated?
couldn't they have menstruated? 	couldn't I have been menstruating?
couldn't you have been menstruating?
couldn't he have been menstruating?
couldn't we have been menstruating?
couldn't you have been menstruating?
couldn't they have been menstruating?