could speculate
Regular verb: speculate - speculated- speculated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could speculate
you could speculate
he could speculate
we could speculate
you could speculate
they could speculate 	I could be speculating
you could be speculating
he could be speculating
we could be speculating
you could be speculating
they could be speculating	I could have speculated
you could have speculated
he could have speculated
we could have speculated
you could have speculated
they could have speculated	I could have been speculating
you could have been speculating
he could have been speculating
we could have been speculating
you could have been speculating
they could have been speculating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't speculate
you couldn't speculate
he couldn't speculate
we couldn't speculate
you couldn't speculate
they couldn't speculate 	I couldn't be speculating
you couldn't be speculating
he couldn't be speculating
we couldn't be speculating
you couldn't be speculating
they couldn't be speculating	I couldn't have speculated
you couldn't have speculated
he couldn't have speculated
we couldn't have speculated
you couldn't have speculated
they couldn't have speculated	I couldn't have been speculating
you couldn't have been speculating
he couldn't have been speculating
we couldn't have been speculating
you couldn't have been speculating
they couldn't have been speculating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I speculate?
could you speculate?
could he speculate?
could we speculate?
could you speculate?
could they speculate? 	could I be speculating?
could you be speculating?
could he be speculating?
could we be speculating?
could you be speculating?
could they be speculating? 	could I have speculated?
could you have speculated?
could he have speculated?
could we have speculated?
could you have speculated?
could they have speculated? 	could I have been speculating?
could you have been speculating?
could he have been speculating?
could we have been speculating?
could you have been speculating?
could they have been speculating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I speculate?
couldn't you speculate?
couldn't he speculate?
couldn't we speculate?
couldn't you speculate?
couldn't they speculate? 	couldn't I be speculating?
couldn't you be speculating?
couldn't he be speculating?
couldn't we be speculating?
couldn't you be speculating?
couldn't they be speculating? 	couldn't I have speculated?
couldn't you have speculated?
couldn't he have speculated?
couldn't we have speculated?
couldn't you have speculated?
couldn't they have speculated? 	couldn't I have been speculating?
couldn't you have been speculating?
couldn't he have been speculating?
couldn't we have been speculating?
couldn't you have been speculating?
couldn't they have been speculating?