I can unbutton you can unbutton she can unbutton we can unbutton you can unbutton they can unbutton
V-ing form
I can be unbuttoning you can be unbuttoning she can be unbuttoning we can be unbuttoning you can be unbuttoning they can be unbuttoning
Perfect
I can have unbuttoned you can have unbuttoned she 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 she can have been unbuttoning we can have been unbuttoning you can have been unbuttoning they can have been unbuttoning
Negation
Simple form
I can't unbutton you can't unbutton she can't unbutton we can't unbutton you can't unbutton they can't unbutton
V-ing form
I can't be unbuttoning you can't be unbuttoning she can't be unbuttoning we can't be unbuttoning you can't be unbuttoning they can't be unbuttoning
Perfect
I can't have unbuttoned you can't have unbuttoned she can't have unbuttoned we can't have unbuttoned you can't have unbuttoned they can't have unbuttoned
V-ing perfect
I can't have been unbuttoning you can't have been unbuttoning she can't have been unbuttoning we can't have been unbuttoning you can't have been unbuttoning they can't have been unbuttoning
Interrogative form
Simple form
can I unbutton? can you unbutton? can she unbutton? can we unbutton? can you unbutton? can they unbutton?
V-ing form
can I be unbuttoning? can you be unbuttoning? can she be unbuttoning? can we be unbuttoning? can you be unbuttoning? can they be unbuttoning?
Perfect
can I have unbuttoned? can you have unbuttoned? can she 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 she have been unbuttoning? can we have been unbuttoning? can you have been unbuttoning? can they have been unbuttoning?
Interro-negative form
Simple form
can't I unbutton? can't you unbutton? can't she unbutton? can't we unbutton? can't you unbutton? can't they unbutton?
V-ing form
can't I be unbuttoning? can't you be unbuttoning? can't she be unbuttoning? can't we be unbuttoning? can't you be unbuttoning? can't they be unbuttoning?
Perfect
can't I have unbuttoned? can't you have unbuttoned? can't she have unbuttoned? can't we have unbuttoned? can't you have unbuttoned? can't they have unbuttoned?
V-ing perfect
can't I have been unbuttoning? can't you have been unbuttoning? can't she have been unbuttoning? can't we have been unbuttoning? can't you have been unbuttoning? can't they have been unbuttoning?