could stud
Regular verb: stud - studded- studded

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could stud
you could stud
he could stud
we could stud
you could stud
they could stud 	I could be studding
you could be studding
he could be studding
we could be studding
you could be studding
they could be studding	I could have studded
you could have studded
he could have studded
we could have studded
you could have studded
they could have studded	I could have been studding
you could have been studding
he could have been studding
we could have been studding
you could have been studding
they could have been studding	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not stud
you could not stud
he could not stud
we could not stud
you could not stud
they could not stud 	I could not be studding
you could not be studding
he could not be studding
we could not be studding
you could not be studding
they could not be studding	I could not have studded
you could not have studded
he could not have studded
we could not have studded
you could not have studded
they could not have studded	I could not have been studding
you could not have been studding
he could not have been studding
we could not have been studding
you could not have been studding
they could not have been studding	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I stud?
could you stud?
could he stud?
could we stud?
could you stud?
could they stud? 	could I be studding?
could you be studding?
could he be studding?
could we be studding?
could you be studding?
could they be studding? 	could I have studded?
could you have studded?
could he have studded?
could we have studded?
could you have studded?
could they have studded? 	could I have been studding?
could you have been studding?
could he have been studding?
could we have been studding?
could you have been studding?
could they have been studding? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not stud?
could you not stud?
could he not stud?
could we not stud?
could you not stud?
could they not stud? 	could I not be studding?
could you not be studding?
could he not be studding?
could we not be studding?
could you not be studding?
could they not be studding? 	could I not have studded?
could you not have studded?
could he not have studded?
could we not have studded?
could you not have studded?
could they not have studded? 	could I not have been studding?
could you not have been studding?
could he not have been studding?
could we not have been studding?
could you not have been studding?
could they not have been studding?