could stud
Verbo regular: stud - studded- studded

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
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	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I couldn't stud
you couldn't stud
he couldn't stud
we couldn't stud
you couldn't stud
they couldn't stud 	I couldn't be studding
you couldn't be studding
he couldn't be studding
we couldn't be studding
you couldn't be studding
they couldn't be studding	I couldn't have studded
you couldn't have studded
he couldn't have studded
we couldn't have studded
you couldn't have studded
they couldn't have studded	I couldn't have been studding
you couldn't have been studding
he couldn't have been studding
we couldn't have been studding
you couldn't have been studding
they couldn't have been studding	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
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? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
couldn't I stud?
couldn't you stud?
couldn't he stud?
couldn't we stud?
couldn't you stud?
couldn't they stud? 	couldn't I be studding?
couldn't you be studding?
couldn't he be studding?
couldn't we be studding?
couldn't you be studding?
couldn't they be studding? 	couldn't I have studded?
couldn't you have studded?
couldn't he have studded?
couldn't we have studded?
couldn't you have studded?
couldn't they have studded? 	couldn't I have been studding?
couldn't you have been studding?
couldn't he have been studding?
couldn't we have been studding?
couldn't you have been studding?
couldn't they have been studding?