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 couldn't trickle you couldn't trickle he couldn't trickle we couldn't trickle you couldn't trickle they couldn't trickle
V-ing form
I couldn't be trickling you couldn't be trickling he couldn't be trickling we couldn't be trickling you couldn't be trickling they couldn't be trickling
Perfect
I couldn't have trickled you couldn't have trickled he couldn't have trickled we couldn't have trickled you couldn't have trickled they couldn't have trickled
V-ing perfect
I couldn't have been trickling you couldn't have been trickling he couldn't have been trickling we couldn't have been trickling you couldn't have been trickling they couldn't 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
couldn't I trickle? couldn't you trickle? couldn't he trickle? couldn't we trickle? couldn't you trickle? couldn't they trickle?
V-ing form
couldn't I be trickling? couldn't you be trickling? couldn't he be trickling? couldn't we be trickling? couldn't you be trickling? couldn't they be trickling?
Perfect
couldn't I have trickled? couldn't you have trickled? couldn't he have trickled? couldn't we have trickled? couldn't you have trickled? couldn't they have trickled?
V-ing perfect
couldn't I have been trickling? couldn't you have been trickling? couldn't he have been trickling? couldn't we have been trickling? couldn't you have been trickling? couldn't they have been trickling?