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 must not sum you must not sum he must not sum we must not sum you must not sum they must not sum	I must not be summing you must not be summing he must not be summing we must not be summing you must not be summing they must not be summing
Perfect	V-ing perfect
I must not have summed you must not have summed he must not have summed we must not have summed you must not have summed they must not have summed	I must not have been summing you must not have been summing he must not have been summing we must not have been summing you must not have been summing they must not 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
must I not sum? must you not sum? must he not sum? must we not sum? must you not sum? must they not sum?	must I not be summing? must you not be summing? must he not be summing? must we not be summing? must you not be summing? must they not be summing?
Perfect	V-ing perfect
must I not have summed? must you not have summed? must he not have summed? must we not have summed? must you not have summed? must they not have summed?	must I not have been summing? must you not have been summing? must he not have been summing? must we not have been summing? must you not have been summing? must they not have been summing?