I could tick you could tick she could tick we could tick you could tick they could tick
V-ing form
I could be ticking you could be ticking she could be ticking we could be ticking you could be ticking they could be ticking
Perfect
I could have ticked you could have ticked she could have ticked we could have ticked you could have ticked they could have ticked
V-ing perfect
I could have been ticking you could have been ticking she could have been ticking we could have been ticking you could have been ticking they could have been ticking
Negation
Simple form
I could not tick you could not tick she could not tick we could not tick you could not tick they could not tick
V-ing form
I could not be ticking you could not be ticking she could not be ticking we could not be ticking you could not be ticking they could not be ticking
Perfect
I could not have ticked you could not have ticked she could not have ticked we could not have ticked you could not have ticked they could not have ticked
V-ing perfect
I could not have been ticking you could not have been ticking she could not have been ticking we could not have been ticking you could not have been ticking they could not have been ticking
Interrogative form
Simple form
could I tick? could you tick? could she tick? could we tick? could you tick? could they tick?
V-ing form
could I be ticking? could you be ticking? could she be ticking? could we be ticking? could you be ticking? could they be ticking?
Perfect
could I have ticked? could you have ticked? could she have ticked? could we have ticked? could you have ticked? could they have ticked?
V-ing perfect
could I have been ticking? could you have been ticking? could she have been ticking? could we have been ticking? could you have been ticking? could they have been ticking?
Interro-negative form
Simple form
could I not tick? could you not tick? could she not tick? could we not tick? could you not tick? could they not tick?
V-ing form
could I not be ticking? could you not be ticking? could she not be ticking? could we not be ticking? could you not be ticking? could they not be ticking?
Perfect
could I not have ticked? could you not have ticked? could she not have ticked? could we not have ticked? could you not have ticked? could they not have ticked?
V-ing perfect
could I not have been ticking? could you not have been ticking? could she not have been ticking? could we not have been ticking? could you not have been ticking? could they not have been ticking?