could substitute
Verbo regular: substitute - substituted- substituted

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could substitute
you could substitute
he could substitute
we could substitute
you could substitute
they could substitute 	I could be substituting
you could be substituting
he could be substituting
we could be substituting
you could be substituting
they could be substituting	I could have substituted
you could have substituted
he could have substituted
we could have substituted
you could have substituted
they could have substituted	I could have been substituting
you could have been substituting
he could have been substituting
we could have been substituting
you could have been substituting
they could have been substituting	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could not substitute
you could not substitute
he could not substitute
we could not substitute
you could not substitute
they could not substitute 	I could not be substituting
you could not be substituting
he could not be substituting
we could not be substituting
you could not be substituting
they could not be substituting	I could not have substituted
you could not have substituted
he could not have substituted
we could not have substituted
you could not have substituted
they could not have substituted	I could not have been substituting
you could not have been substituting
he could not have been substituting
we could not have been substituting
you could not have been substituting
they could not have been substituting	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I substitute?
could you substitute?
could he substitute?
could we substitute?
could you substitute?
could they substitute? 	could I be substituting?
could you be substituting?
could he be substituting?
could we be substituting?
could you be substituting?
could they be substituting? 	could I have substituted?
could you have substituted?
could he have substituted?
could we have substituted?
could you have substituted?
could they have substituted? 	could I have been substituting?
could you have been substituting?
could he have been substituting?
could we have been substituting?
could you have been substituting?
could they have been substituting? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I not substitute?
could you not substitute?
could he not substitute?
could we not substitute?
could you not substitute?
could they not substitute? 	could I not be substituting?
could you not be substituting?
could he not be substituting?
could we not be substituting?
could you not be substituting?
could they not be substituting? 	could I not have substituted?
could you not have substituted?
could he not have substituted?
could we not have substituted?
could you not have substituted?
could they not have substituted? 	could I not have been substituting?
could you not have been substituting?
could he not have been substituting?
could we not have been substituting?
could you not have been substituting?
could they not have been substituting?