I could babysit you could babysit she could babysit we could babysit you could babysit they could babysit
V-ing form
I could be babysiting you could be babysiting she could be babysiting we could be babysiting you could be babysiting they could be babysiting
Perfect
I could have babysat you could have babysat she could have babysat we could have babysat you could have babysat they could have babysat
V-ing perfect
I could have been babysiting you could have been babysiting she could have been babysiting we could have been babysiting you could have been babysiting they could have been babysiting
Negation
Simple form
I couldn't babysit you couldn't babysit she couldn't babysit we couldn't babysit you couldn't babysit they couldn't babysit
V-ing form
I couldn't be babysiting you couldn't be babysiting she couldn't be babysiting we couldn't be babysiting you couldn't be babysiting they couldn't be babysiting
Perfect
I couldn't have babysat you couldn't have babysat she couldn't have babysat we couldn't have babysat you couldn't have babysat they couldn't have babysat
V-ing perfect
I couldn't have been babysiting you couldn't have been babysiting she couldn't have been babysiting we couldn't have been babysiting you couldn't have been babysiting they couldn't have been babysiting
Interrogative form
Simple form
could I babysit? could you babysit? could she babysit? could we babysit? could you babysit? could they babysit?
V-ing form
could I be babysiting? could you be babysiting? could she be babysiting? could we be babysiting? could you be babysiting? could they be babysiting?
Perfect
could I have babysat? could you have babysat? could she have babysat? could we have babysat? could you have babysat? could they have babysat?
V-ing perfect
could I have been babysiting? could you have been babysiting? could she have been babysiting? could we have been babysiting? could you have been babysiting? could they have been babysiting?
Interro-negative form
Simple form
couldn't I babysit? couldn't you babysit? couldn't she babysit? couldn't we babysit? couldn't you babysit? couldn't they babysit?
V-ing form
couldn't I be babysiting? couldn't you be babysiting? couldn't she be babysiting? couldn't we be babysiting? couldn't you be babysiting? couldn't they be babysiting?
Perfect
couldn't I have babysat? couldn't you have babysat? couldn't she have babysat? couldn't we have babysat? couldn't you have babysat? couldn't they have babysat?
V-ing perfect
couldn't I have been babysiting? couldn't you have been babysiting? couldn't she have been babysiting? couldn't we have been babysiting? couldn't you have been babysiting? couldn't they have been babysiting?