must sniff
Regular verb: sniff - sniffed- sniffed

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

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

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

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