English verb conjugation
MUST BURR

Regular verb: burr - burred - burred

Affirmation

Simple form	V-ing form
I must burr you must burr he must burr we must burr you must burr they must burr	I must be burring you must be burring he must be burring we must be burring you must be burring they must be burring
Perfect	V-ing perfect
I must have burred you must have burred he must have burred we must have burred you must have burred they must have burred	I must have been burring you must have been burring he must have been burring we must have been burring you must have been burring they must have been burring

Negation

Simple form	V-ing form
I mustn't burr you mustn't burr he mustn't burr we mustn't burr you mustn't burr they mustn't burr	I mustn't be burring you mustn't be burring he mustn't be burring we mustn't be burring you mustn't be burring they mustn't be burring
Perfect	V-ing perfect
I mustn't have burred you mustn't have burred he mustn't have burred we mustn't have burred you mustn't have burred they mustn't have burred	I mustn't have been burring you mustn't have been burring he mustn't have been burring we mustn't have been burring you mustn't have been burring they mustn't have been burring

Interrogative form

Simple form	V-ing form
must I burr? must you burr? must he burr? must we burr? must you burr? must they burr?	must I be burring? must you be burring? must he be burring? must we be burring? must you be burring? must they be burring?
Perfect	V-ing perfect
must I have burred? must you have burred? must he have burred? must we have burred? must you have burred? must they have burred?	must I have been burring? must you have been burring? must he have been burring? must we have been burring? must you have been burring? must they have been burring?

Interro-negative form

Simple form	V-ing form
mustn't I burr? mustn't you burr? mustn't he burr? mustn't we burr? mustn't you burr? mustn't they burr?	mustn't I be burring? mustn't you be burring? mustn't he be burring? mustn't we be burring? mustn't you be burring? mustn't they be burring?
Perfect	V-ing perfect
mustn't I have burred? mustn't you have burred? mustn't he have burred? mustn't we have burred? mustn't you have burred? mustn't they have burred?	mustn't I have been burring? mustn't you have been burring? mustn't he have been burring? mustn't we have been burring? mustn't you have been burring? mustn't they have been burring?