could check
Verbo regular: check - checked- checked

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could check
you could check
he could check
we could check
you could check
they could check 	I could be checking
you could be checking
he could be checking
we could be checking
you could be checking
they could be checking	I could have checked
you could have checked
he could have checked
we could have checked
you could have checked
they could have checked	I could have been checking
you could have been checking
he could have been checking
we could have been checking
you could have been checking
they could have been checking	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I couldn't check
you couldn't check
he couldn't check
we couldn't check
you couldn't check
they couldn't check 	I couldn't be checking
you couldn't be checking
he couldn't be checking
we couldn't be checking
you couldn't be checking
they couldn't be checking	I couldn't have checked
you couldn't have checked
he couldn't have checked
we couldn't have checked
you couldn't have checked
they couldn't have checked	I couldn't have been checking
you couldn't have been checking
he couldn't have been checking
we couldn't have been checking
you couldn't have been checking
they couldn't have been checking	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I check?
could you check?
could he check?
could we check?
could you check?
could they check? 	could I be checking?
could you be checking?
could he be checking?
could we be checking?
could you be checking?
could they be checking? 	could I have checked?
could you have checked?
could he have checked?
could we have checked?
could you have checked?
could they have checked? 	could I have been checking?
could you have been checking?
could he have been checking?
could we have been checking?
could you have been checking?
could they have been checking? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
couldn't I check?
couldn't you check?
couldn't he check?
couldn't we check?
couldn't you check?
couldn't they check? 	couldn't I be checking?
couldn't you be checking?
couldn't he be checking?
couldn't we be checking?
couldn't you be checking?
couldn't they be checking? 	couldn't I have checked?
couldn't you have checked?
couldn't he have checked?
couldn't we have checked?
couldn't you have checked?
couldn't they have checked? 	couldn't I have been checking?
couldn't you have been checking?
couldn't he have been checking?
couldn't we have been checking?
couldn't you have been checking?
couldn't they have been checking?