English verb conjugation
MUST SNIFF

Regular verb: sniff - sniffed - sniffed

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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
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
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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?