I could tick you could tick he could tick we could tick you could tick they could tick
V-ing form
I could be ticking you could be ticking he could be ticking we could be ticking you could be ticking they could be ticking
Perfect
I could have ticked you could have ticked he 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 he 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 he 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 he 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 he 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 he 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 he tick? could we tick? could you tick? could they tick?
V-ing form
could I be ticking? could you be ticking? could he be ticking? could we be ticking? could you be ticking? could they be ticking?
Perfect
could I have ticked? could you have ticked? could he 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 he 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 he 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 he 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 he 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 he not have been ticking? could we not have been ticking? could you not have been ticking? could they not have been ticking?