English verb conjugation
MUST SUM

Regular verb: sum - summed - summed

Affirmation

Simple form	V-ing form
I must sum you must sum he must sum we must sum you must sum they must sum	I must be summing you must be summing he must be summing we must be summing you must be summing they must be summing
Perfect	V-ing perfect
I must have summed you must have summed he must have summed we must have summed you must have summed they must have summed	I must have been summing you must have been summing he must have been summing we must have been summing you must have been summing they must have been summing

Negation

Simple form	V-ing form
I mustn't sum you mustn't sum he mustn't sum we mustn't sum you mustn't sum they mustn't sum	I mustn't be summing you mustn't be summing he mustn't be summing we mustn't be summing you mustn't be summing they mustn't be summing
Perfect	V-ing perfect
I mustn't have summed you mustn't have summed he mustn't have summed we mustn't have summed you mustn't have summed they mustn't have summed	I mustn't have been summing you mustn't have been summing he mustn't have been summing we mustn't have been summing you mustn't have been summing they mustn't have been summing

Interrogative form

Simple form	V-ing form
must I sum? must you sum? must he sum? must we sum? must you sum? must they sum?	must I be summing? must you be summing? must he be summing? must we be summing? must you be summing? must they be summing?
Perfect	V-ing perfect
must I have summed? must you have summed? must he have summed? must we have summed? must you have summed? must they have summed?	must I have been summing? must you have been summing? must he have been summing? must we have been summing? must you have been summing? must they have been summing?

Interro-negative form

Simple form	V-ing form
mustn't I sum? mustn't you sum? mustn't he sum? mustn't we sum? mustn't you sum? mustn't they sum?	mustn't I be summing? mustn't you be summing? mustn't he be summing? mustn't we be summing? mustn't you be summing? mustn't they be summing?
Perfect	V-ing perfect
mustn't I have summed? mustn't you have summed? mustn't he have summed? mustn't we have summed? mustn't you have summed? mustn't they have summed?	mustn't I have been summing? mustn't you have been summing? mustn't he have been summing? mustn't we have been summing? mustn't you have been summing? mustn't they have been summing?