I could prescribe you could prescribe he could prescribe we could prescribe you could prescribe they could prescribe
V-ing form
I could be prescribing you could be prescribing he could be prescribing we could be prescribing you could be prescribing they could be prescribing
Perfect
I could have prescribed you could have prescribed he could have prescribed we could have prescribed you could have prescribed they could have prescribed
V-ing perfect
I could have been prescribing you could have been prescribing he could have been prescribing we could have been prescribing you could have been prescribing they could have been prescribing
Negation
Simple form
I couldn't prescribe you couldn't prescribe he couldn't prescribe we couldn't prescribe you couldn't prescribe they couldn't prescribe
V-ing form
I couldn't be prescribing you couldn't be prescribing he couldn't be prescribing we couldn't be prescribing you couldn't be prescribing they couldn't be prescribing
Perfect
I couldn't have prescribed you couldn't have prescribed he couldn't have prescribed we couldn't have prescribed you couldn't have prescribed they couldn't have prescribed
V-ing perfect
I couldn't have been prescribing you couldn't have been prescribing he couldn't have been prescribing we couldn't have been prescribing you couldn't have been prescribing they couldn't have been prescribing
Interrogative form
Simple form
could I prescribe? could you prescribe? could he prescribe? could we prescribe? could you prescribe? could they prescribe?
V-ing form
could I be prescribing? could you be prescribing? could he be prescribing? could we be prescribing? could you be prescribing? could they be prescribing?
Perfect
could I have prescribed? could you have prescribed? could he have prescribed? could we have prescribed? could you have prescribed? could they have prescribed?
V-ing perfect
could I have been prescribing? could you have been prescribing? could he have been prescribing? could we have been prescribing? could you have been prescribing? could they have been prescribing?
Interro-negative form
Simple form
couldn't I prescribe? couldn't you prescribe? couldn't he prescribe? couldn't we prescribe? couldn't you prescribe? couldn't they prescribe?
V-ing form
couldn't I be prescribing? couldn't you be prescribing? couldn't he be prescribing? couldn't we be prescribing? couldn't you be prescribing? couldn't they be prescribing?
Perfect
couldn't I have prescribed? couldn't you have prescribed? couldn't he have prescribed? couldn't we have prescribed? couldn't you have prescribed? couldn't they have prescribed?
V-ing perfect
couldn't I have been prescribing? couldn't you have been prescribing? couldn't he have been prescribing? couldn't we have been prescribing? couldn't you have been prescribing? couldn't they have been prescribing?