English verb conjugation
MUST PURR

Regular verb: purr - purred - purred

Affirmation

Simple form	V-ing form
I must purr you must purr she must purr we must purr you must purr they must purr	I must be purring you must be purring she must be purring we must be purring you must be purring they must be purring
Perfect	V-ing perfect
I must have purred you must have purred she must have purred we must have purred you must have purred they must have purred	I must have been purring you must have been purring she must have been purring we must have been purring you must have been purring they must have been purring

Negation

Simple form	V-ing form
I must not purr you must not purr she must not purr we must not purr you must not purr they must not purr	I must not be purring you must not be purring she must not be purring we must not be purring you must not be purring they must not be purring
Perfect	V-ing perfect
I must not have purred you must not have purred she must not have purred we must not have purred you must not have purred they must not have purred	I must not have been purring you must not have been purring she must not have been purring we must not have been purring you must not have been purring they must not have been purring

Interrogative form

Simple form	V-ing form
must I purr? must you purr? must she purr? must we purr? must you purr? must they purr?	must I be purring? must you be purring? must she be purring? must we be purring? must you be purring? must they be purring?
Perfect	V-ing perfect
must I have purred? must you have purred? must she have purred? must we have purred? must you have purred? must they have purred?	must I have been purring? must you have been purring? must she have been purring? must we have been purring? must you have been purring? must they have been purring?

Interro-negative form

Simple form	V-ing form
must I not purr? must you not purr? must she not purr? must we not purr? must you not purr? must they not purr?	must I not be purring? must you not be purring? must she not be purring? must we not be purring? must you not be purring? must they not be purring?
Perfect	V-ing perfect
must I not have purred? must you not have purred? must she not have purred? must we not have purred? must you not have purred? must they not have purred?	must I not have been purring? must you not have been purring? must she not have been purring? must we not have been purring? must you not have been purring? must they not have been purring?