I could trickle you could trickle he could trickle we could trickle you could trickle they could trickle
V-ing form
I could be trickling you could be trickling he could be trickling we could be trickling you could be trickling they could be trickling
Perfect
I could have trickled you could have trickled he could have trickled we could have trickled you could have trickled they could have trickled
V-ing perfect
I could have been trickling you could have been trickling he could have been trickling we could have been trickling you could have been trickling they could have been trickling
Negation
Simple form
I could not trickle you could not trickle he could not trickle we could not trickle you could not trickle they could not trickle
V-ing form
I could not be trickling you could not be trickling he could not be trickling we could not be trickling you could not be trickling they could not be trickling
Perfect
I could not have trickled you could not have trickled he could not have trickled we could not have trickled you could not have trickled they could not have trickled
V-ing perfect
I could not have been trickling you could not have been trickling he could not have been trickling we could not have been trickling you could not have been trickling they could not have been trickling
Interrogative form
Simple form
could I trickle? could you trickle? could he trickle? could we trickle? could you trickle? could they trickle?
V-ing form
could I be trickling? could you be trickling? could he be trickling? could we be trickling? could you be trickling? could they be trickling?
Perfect
could I have trickled? could you have trickled? could he have trickled? could we have trickled? could you have trickled? could they have trickled?
V-ing perfect
could I have been trickling? could you have been trickling? could he have been trickling? could we have been trickling? could you have been trickling? could they have been trickling?
Interro-negative form
Simple form
could I not trickle? could you not trickle? could he not trickle? could we not trickle? could you not trickle? could they not trickle?
V-ing form
could I not be trickling? could you not be trickling? could he not be trickling? could we not be trickling? could you not be trickling? could they not be trickling?
Perfect
could I not have trickled? could you not have trickled? could he not have trickled? could we not have trickled? could you not have trickled? could they not have trickled?
V-ing perfect
could I not have been trickling? could you not have been trickling? could he not have been trickling? could we not have been trickling? could you not have been trickling? could they not have been trickling?