Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I must knock knock you must knock knock she must knock knock we must knock knock you must knock knock they must knock knock
V-ing form
I must be knock knocking you must be knock knocking she must be knock knocking we must be knock knocking you must be knock knocking they must be knock knocking
Perfect
I must have knock knocked you must have knock knocked she must have knock knocked we must have knock knocked you must have knock knocked they must have knock knocked
V-ing perfect
I must have been knock knocking you must have been knock knocking she must have been knock knocking we must have been knock knocking you must have been knock knocking they must have been knock knocking
Negation
Simple form
I mustn't knock knock you mustn't knock knock she mustn't knock knock we mustn't knock knock you mustn't knock knock they mustn't knock knock
V-ing form
I mustn't be knock knocking you mustn't be knock knocking she mustn't be knock knocking we mustn't be knock knocking you mustn't be knock knocking they mustn't be knock knocking
Perfect
I mustn't have knock knocked you mustn't have knock knocked she mustn't have knock knocked we mustn't have knock knocked you mustn't have knock knocked they mustn't have knock knocked
V-ing perfect
I mustn't have been knock knocking you mustn't have been knock knocking she mustn't have been knock knocking we mustn't have been knock knocking you mustn't have been knock knocking they mustn't have been knock knocking
Interrogative form
Simple form
must I knock knock? must you knock knock? must she knock knock? must we knock knock? must you knock knock? must they knock knock?
V-ing form
must I be knock knocking? must you be knock knocking? must she be knock knocking? must we be knock knocking? must you be knock knocking? must they be knock knocking?
Perfect
must I have knock knocked? must you have knock knocked? must she have knock knocked? must we have knock knocked? must you have knock knocked? must they have knock knocked?
V-ing perfect
must I have been knock knocking? must you have been knock knocking? must she have been knock knocking? must we have been knock knocking? must you have been knock knocking? must they have been knock knocking?
Interro-negative form
Simple form
mustn't I knock knock? mustn't you knock knock? mustn't she knock knock? mustn't we knock knock? mustn't you knock knock? mustn't they knock knock?
V-ing form
mustn't I be knock knocking? mustn't you be knock knocking? mustn't she be knock knocking? mustn't we be knock knocking? mustn't you be knock knocking? mustn't they be knock knocking?
Perfect
mustn't I have knock knocked? mustn't you have knock knocked? mustn't she have knock knocked? mustn't we have knock knocked? mustn't you have knock knocked? mustn't they have knock knocked?
V-ing perfect
mustn't I have been knock knocking? mustn't you have been knock knocking? mustn't she have been knock knocking? mustn't we have been knock knocking? mustn't you have been knock knocking? mustn't they have been knock knocking?