could sniff
Verbo regular: sniff - sniffed- sniffed

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could sniff
you could sniff
he could sniff
we could sniff
you could sniff
they could sniff 	I could be sniffing
you could be sniffing
he could be sniffing
we could be sniffing
you could be sniffing
they could be sniffing	I could have sniffed
you could have sniffed
he could have sniffed
we could have sniffed
you could have sniffed
they could have sniffed	I could have been sniffing
you could have been sniffing
he could have been sniffing
we could have been sniffing
you could have been sniffing
they could have been sniffing	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I could not sniff
you could not sniff
he could not sniff
we could not sniff
you could not sniff
they could not sniff 	I could not be sniffing
you could not be sniffing
he could not be sniffing
we could not be sniffing
you could not be sniffing
they could not be sniffing	I could not have sniffed
you could not have sniffed
he could not have sniffed
we could not have sniffed
you could not have sniffed
they could not have sniffed	I could not have been sniffing
you could not have been sniffing
he could not have been sniffing
we could not have been sniffing
you could not have been sniffing
they could not have been sniffing	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I sniff?
could you sniff?
could he sniff?
could we sniff?
could you sniff?
could they sniff? 	could I be sniffing?
could you be sniffing?
could he be sniffing?
could we be sniffing?
could you be sniffing?
could they be sniffing? 	could I have sniffed?
could you have sniffed?
could he have sniffed?
could we have sniffed?
could you have sniffed?
could they have sniffed? 	could I have been sniffing?
could you have been sniffing?
could he have been sniffing?
could we have been sniffing?
could you have been sniffing?
could they have been sniffing? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
could I not sniff?
could you not sniff?
could he not sniff?
could we not sniff?
could you not sniff?
could they not sniff? 	could I not be sniffing?
could you not be sniffing?
could he not be sniffing?
could we not be sniffing?
could you not be sniffing?
could they not be sniffing? 	could I not have sniffed?
could you not have sniffed?
could he not have sniffed?
could we not have sniffed?
could you not have sniffed?
could they not have sniffed? 	could I not have been sniffing?
could you not have been sniffing?
could he not have been sniffing?
could we not have been sniffing?
could you not have been sniffing?
could they not have been sniffing?