can sniff
Regular verb: sniff - sniffed- sniffed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can sniff
you can sniff
he can sniff
we can sniff
you can sniff
they can sniff 	I can be sniffing
you can be sniffing
he can be sniffing
we can be sniffing
you can be sniffing
they can be sniffing	I can have sniffed
you can have sniffed
he can have sniffed
we can have sniffed
you can have sniffed
they can have sniffed	I can have been sniffing
you can have been sniffing
he can have been sniffing
we can have been sniffing
you can have been sniffing
they can have been sniffing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I cannot sniff
you cannot sniff
he cannot sniff
we cannot sniff
you cannot sniff
they cannot sniff 	I cannot be sniffing
you cannot be sniffing
he cannot be sniffing
we cannot be sniffing
you cannot be sniffing
they cannot be sniffing	I cannot have sniffed
you cannot have sniffed
he cannot have sniffed
we cannot have sniffed
you cannot have sniffed
they cannot have sniffed	I cannot have been sniffing
you cannot have been sniffing
he cannot have been sniffing
we cannot have been sniffing
you cannot have been sniffing
they cannot have been sniffing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I sniff?
can you sniff?
can he sniff?
can we sniff?
can you sniff?
can they sniff? 	can I be sniffing?
can you be sniffing?
can he be sniffing?
can we be sniffing?
can you be sniffing?
can they be sniffing? 	can I have sniffed?
can you have sniffed?
can he have sniffed?
can we have sniffed?
can you have sniffed?
can they have sniffed? 	can I have been sniffing?
can you have been sniffing?
can he have been sniffing?
can we have been sniffing?
can you have been sniffing?
can they have been sniffing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I not sniff?
can you not sniff?
can he not sniff?
can we not sniff?
can you not sniff?
can they not sniff? 	can I not be sniffing?
can you not be sniffing?
can he not be sniffing?
can we not be sniffing?
can you not be sniffing?
can they not be sniffing? 	can I not have sniffed?
can you not have sniffed?
can he not have sniffed?
can we not have sniffed?
can you not have sniffed?
can they not have sniffed? 	can I not have been sniffing?
can you not have been sniffing?
can he not have been sniffing?
can we not have been sniffing?
can you not have been sniffing?
can they not have been sniffing?