I can unbutton you can unbutton he can unbutton we can unbutton you can unbutton they can unbutton
V-ing form
I can be unbuttoning you can be unbuttoning he can be unbuttoning we can be unbuttoning you can be unbuttoning they can be unbuttoning
Perfect
I can have unbuttoned you can have unbuttoned he can have unbuttoned we can have unbuttoned you can have unbuttoned they can have unbuttoned
V-ing perfect
I can have been unbuttoning you can have been unbuttoning he can have been unbuttoning we can have been unbuttoning you can have been unbuttoning they can have been unbuttoning
Negation
Simple form
I cannot unbutton you cannot unbutton he cannot unbutton we cannot unbutton you cannot unbutton they cannot unbutton
V-ing form
I cannot be unbuttoning you cannot be unbuttoning he cannot be unbuttoning we cannot be unbuttoning you cannot be unbuttoning they cannot be unbuttoning
Perfect
I cannot have unbuttoned you cannot have unbuttoned he cannot have unbuttoned we cannot have unbuttoned you cannot have unbuttoned they cannot have unbuttoned
V-ing perfect
I cannot have been unbuttoning you cannot have been unbuttoning he cannot have been unbuttoning we cannot have been unbuttoning you cannot have been unbuttoning they cannot have been unbuttoning
Interrogative form
Simple form
can I unbutton? can you unbutton? can he unbutton? can we unbutton? can you unbutton? can they unbutton?
V-ing form
can I be unbuttoning? can you be unbuttoning? can he be unbuttoning? can we be unbuttoning? can you be unbuttoning? can they be unbuttoning?
Perfect
can I have unbuttoned? can you have unbuttoned? can he have unbuttoned? can we have unbuttoned? can you have unbuttoned? can they have unbuttoned?
V-ing perfect
can I have been unbuttoning? can you have been unbuttoning? can he have been unbuttoning? can we have been unbuttoning? can you have been unbuttoning? can they have been unbuttoning?
Interro-negative form
Simple form
can I not unbutton? can you not unbutton? can he not unbutton? can we not unbutton? can you not unbutton? can they not unbutton?
V-ing form
can I not be unbuttoning? can you not be unbuttoning? can he not be unbuttoning? can we not be unbuttoning? can you not be unbuttoning? can they not be unbuttoning?
Perfect
can I not have unbuttoned? can you not have unbuttoned? can he not have unbuttoned? can we not have unbuttoned? can you not have unbuttoned? can they not have unbuttoned?
V-ing perfect
can I not have been unbuttoning? can you not have been unbuttoning? can he not have been unbuttoning? can we not have been unbuttoning? can you not have been unbuttoning? can they not have been unbuttoning?