could prevent
Verbo regular: prevent - prevented- prevented

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could prevent
you could prevent
he could prevent
we could prevent
you could prevent
they could prevent 	I could be preventing
you could be preventing
he could be preventing
we could be preventing
you could be preventing
they could be preventing	I could have prevented
you could have prevented
he could have prevented
we could have prevented
you could have prevented
they could have prevented	I could have been preventing
you could have been preventing
he could have been preventing
we could have been preventing
you could have been preventing
they could have been preventing	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I couldn't prevent
you couldn't prevent
he couldn't prevent
we couldn't prevent
you couldn't prevent
they couldn't prevent 	I couldn't be preventing
you couldn't be preventing
he couldn't be preventing
we couldn't be preventing
you couldn't be preventing
they couldn't be preventing	I couldn't have prevented
you couldn't have prevented
he couldn't have prevented
we couldn't have prevented
you couldn't have prevented
they couldn't have prevented	I couldn't have been preventing
you couldn't have been preventing
he couldn't have been preventing
we couldn't have been preventing
you couldn't have been preventing
they couldn't have been preventing	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I prevent?
could you prevent?
could he prevent?
could we prevent?
could you prevent?
could they prevent? 	could I be preventing?
could you be preventing?
could he be preventing?
could we be preventing?
could you be preventing?
could they be preventing? 	could I have prevented?
could you have prevented?
could he have prevented?
could we have prevented?
could you have prevented?
could they have prevented? 	could I have been preventing?
could you have been preventing?
could he have been preventing?
could we have been preventing?
could you have been preventing?
could they have been preventing? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
couldn't I prevent?
couldn't you prevent?
couldn't he prevent?
couldn't we prevent?
couldn't you prevent?
couldn't they prevent? 	couldn't I be preventing?
couldn't you be preventing?
couldn't he be preventing?
couldn't we be preventing?
couldn't you be preventing?
couldn't they be preventing? 	couldn't I have prevented?
couldn't you have prevented?
couldn't he have prevented?
couldn't we have prevented?
couldn't you have prevented?
couldn't they have prevented? 	couldn't I have been preventing?
couldn't you have been preventing?
couldn't he have been preventing?
couldn't we have been preventing?
couldn't you have been preventing?
couldn't they have been preventing?