could collaborate
Regular verb: collaborate - collaborated- collaborated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could collaborate
you could collaborate
she could collaborate
we could collaborate
you could collaborate
they could collaborate 	I could be collaborating
you could be collaborating
she could be collaborating
we could be collaborating
you could be collaborating
they could be collaborating	I could have collaborated
you could have collaborated
she could have collaborated
we could have collaborated
you could have collaborated
they could have collaborated	I could have been collaborating
you could have been collaborating
she could have been collaborating
we could have been collaborating
you could have been collaborating
they could have been collaborating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not collaborate
you could not collaborate
she could not collaborate
we could not collaborate
you could not collaborate
they could not collaborate 	I could not be collaborating
you could not be collaborating
she could not be collaborating
we could not be collaborating
you could not be collaborating
they could not be collaborating	I could not have collaborated
you could not have collaborated
she could not have collaborated
we could not have collaborated
you could not have collaborated
they could not have collaborated	I could not have been collaborating
you could not have been collaborating
she could not have been collaborating
we could not have been collaborating
you could not have been collaborating
they could not have been collaborating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I collaborate?
could you collaborate?
could she collaborate?
could we collaborate?
could you collaborate?
could they collaborate? 	could I be collaborating?
could you be collaborating?
could she be collaborating?
could we be collaborating?
could you be collaborating?
could they be collaborating? 	could I have collaborated?
could you have collaborated?
could she have collaborated?
could we have collaborated?
could you have collaborated?
could they have collaborated? 	could I have been collaborating?
could you have been collaborating?
could she have been collaborating?
could we have been collaborating?
could you have been collaborating?
could they have been collaborating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not collaborate?
could you not collaborate?
could she not collaborate?
could we not collaborate?
could you not collaborate?
could they not collaborate? 	could I not be collaborating?
could you not be collaborating?
could she not be collaborating?
could we not be collaborating?
could you not be collaborating?
could they not be collaborating? 	could I not have collaborated?
could you not have collaborated?
could she not have collaborated?
could we not have collaborated?
could you not have collaborated?
could they not have collaborated? 	could I not have been collaborating?
could you not have been collaborating?
could she not have been collaborating?
could we not have been collaborating?
could you not have been collaborating?
could they not have been collaborating?