English verb conjugation
MUST HISS

Regular verb: hiss - hissed - hissed

Affirmation

Simple form	V-ing form
I must hiss you must hiss he must hiss we must hiss you must hiss they must hiss	I must be hissing you must be hissing he must be hissing we must be hissing you must be hissing they must be hissing
Perfect	V-ing perfect
I must have hissed you must have hissed he must have hissed we must have hissed you must have hissed they must have hissed	I must have been hissing you must have been hissing he must have been hissing we must have been hissing you must have been hissing they must have been hissing

Negation

Simple form	V-ing form
I must not hiss you must not hiss he must not hiss we must not hiss you must not hiss they must not hiss	I must not be hissing you must not be hissing he must not be hissing we must not be hissing you must not be hissing they must not be hissing
Perfect	V-ing perfect
I must not have hissed you must not have hissed he must not have hissed we must not have hissed you must not have hissed they must not have hissed	I must not have been hissing you must not have been hissing he must not have been hissing we must not have been hissing you must not have been hissing they must not have been hissing

Interrogative form

Simple form	V-ing form
must I hiss? must you hiss? must he hiss? must we hiss? must you hiss? must they hiss?	must I be hissing? must you be hissing? must he be hissing? must we be hissing? must you be hissing? must they be hissing?
Perfect	V-ing perfect
must I have hissed? must you have hissed? must he have hissed? must we have hissed? must you have hissed? must they have hissed?	must I have been hissing? must you have been hissing? must he have been hissing? must we have been hissing? must you have been hissing? must they have been hissing?

Interro-negative form

Simple form	V-ing form
must I not hiss? must you not hiss? must he not hiss? must we not hiss? must you not hiss? must they not hiss?	must I not be hissing? must you not be hissing? must he not be hissing? must we not be hissing? must you not be hissing? must they not be hissing?
Perfect	V-ing perfect
must I not have hissed? must you not have hissed? must he not have hissed? must we not have hissed? must you not have hissed? must they not have hissed?	must I not have been hissing? must you not have been hissing? must he not have been hissing? must we not have been hissing? must you not have been hissing? must they not have been hissing?