I may sum you may sum he may sum we may sum you may sum they may sum
V-ing form
I may be summing you may be summing he may be summing we may be summing you may be summing they may be summing
Perfect
I may have summed you may have summed he may have summed we may have summed you may have summed they may have summed
V-ing perfect
I may have been summing you may have been summing he may have been summing we may have been summing you may have been summing they may have been summing
Negation
Simple form
I may not sum you may not sum he may not sum we may not sum you may not sum they may not sum
V-ing form
I may not be summing you may not be summing he may not be summing we may not be summing you may not be summing they may not be summing
Perfect
I may not have summed you may not have summed he may not have summed we may not have summed you may not have summed they may not have summed
V-ing perfect
I may not have been summing you may not have been summing he may not have been summing we may not have been summing you may not have been summing they may not have been summing
Interrogative form
Simple form
may I sum? may you sum? may he sum? may we sum? may you sum? may they sum?
V-ing form
may I be summing? may you be summing? may he be summing? may we be summing? may you be summing? may they be summing?
Perfect
may I have summed? may you have summed? may he have summed? may we have summed? may you have summed? may they have summed?
V-ing perfect
may I have been summing? may you have been summing? may he have been summing? may we have been summing? may you have been summing? may they have been summing?
Interro-negative form
Simple form
may I not sum? may you not sum? may he not sum? may we not sum? may you not sum? may they not sum?
V-ing form
may I not be summing? may you not be summing? may he not be summing? may we not be summing? may you not be summing? may they not be summing?
Perfect
may I not have summed? may you not have summed? may he not have summed? may we not have summed? may you not have summed? may they not have summed?
V-ing perfect
may I not have been summing? may you not have been summing? may he not have been summing? may we not have been summing? may you not have been summing? may they not have been summing?