I could fish you could fish he could fish we could fish you could fish they could fish
V-ing form
I could be fishing you could be fishing he could be fishing we could be fishing you could be fishing they could be fishing
Perfect
I could have fished you could have fished he could have fished we could have fished you could have fished they could have fished
V-ing perfect
I could have been fishing you could have been fishing he could have been fishing we could have been fishing you could have been fishing they could have been fishing
Negation
Simple form
I could not fish you could not fish he could not fish we could not fish you could not fish they could not fish
V-ing form
I could not be fishing you could not be fishing he could not be fishing we could not be fishing you could not be fishing they could not be fishing
Perfect
I could not have fished you could not have fished he could not have fished we could not have fished you could not have fished they could not have fished
V-ing perfect
I could not have been fishing you could not have been fishing he could not have been fishing we could not have been fishing you could not have been fishing they could not have been fishing
Interrogative form
Simple form
could I fish? could you fish? could he fish? could we fish? could you fish? could they fish?
V-ing form
could I be fishing? could you be fishing? could he be fishing? could we be fishing? could you be fishing? could they be fishing?
Perfect
could I have fished? could you have fished? could he have fished? could we have fished? could you have fished? could they have fished?
V-ing perfect
could I have been fishing? could you have been fishing? could he have been fishing? could we have been fishing? could you have been fishing? could they have been fishing?
Interro-negative form
Simple form
could I not fish? could you not fish? could he not fish? could we not fish? could you not fish? could they not fish?
V-ing form
could I not be fishing? could you not be fishing? could he not be fishing? could we not be fishing? could you not be fishing? could they not be fishing?
Perfect
could I not have fished? could you not have fished? could he not have fished? could we not have fished? could you not have fished? could they not have fished?
V-ing perfect
could I not have been fishing? could you not have been fishing? could he not have been fishing? could we not have been fishing? could you not have been fishing? could they not have been fishing?