can knock
Verbo regular: knock - knocked- knocked

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I can knock
you can knock
she can knock
we can knock
you can knock
they can knock 	I can be knocking
you can be knocking
she can be knocking
we can be knocking
you can be knocking
they can be knocking	I can have knocked
you can have knocked
she can have knocked
we can have knocked
you can have knocked
they can have knocked	I can have been knocking
you can have been knocking
she can have been knocking
we can have been knocking
you can have been knocking
they can have been knocking	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I can't knock
you can't knock
she can't knock
we can't knock
you can't knock
they can't knock 	I can't be knocking
you can't be knocking
she can't be knocking
we can't be knocking
you can't be knocking
they can't be knocking	I can't have knocked
you can't have knocked
she can't have knocked
we can't have knocked
you can't have knocked
they can't have knocked	I can't have been knocking
you can't have been knocking
she can't have been knocking
we can't have been knocking
you can't have been knocking
they can't have been knocking	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
can I knock?
can you knock?
can she knock?
can we knock?
can you knock?
can they knock? 	can I be knocking?
can you be knocking?
can she be knocking?
can we be knocking?
can you be knocking?
can they be knocking? 	can I have knocked?
can you have knocked?
can she have knocked?
can we have knocked?
can you have knocked?
can they have knocked? 	can I have been knocking?
can you have been knocking?
can she have been knocking?
can we have been knocking?
can you have been knocking?
can they have been knocking? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
can't I knock?
can't you knock?
can't she knock?
can't we knock?
can't you knock?
can't they knock? 	can't I be knocking?
can't you be knocking?
can't she be knocking?
can't we be knocking?
can't you be knocking?
can't they be knocking? 	can't I have knocked?
can't you have knocked?
can't she have knocked?
can't we have knocked?
can't you have knocked?
can't they have knocked? 	can't I have been knocking?
can't you have been knocking?
can't she have been knocking?
can't we have been knocking?
can't you have been knocking?
can't they have been knocking?