I could quench you could quench he could quench we could quench you could quench they could quench
V-ing form
I could be quenching you could be quenching he could be quenching we could be quenching you could be quenching they could be quenching
Perfect
I could have quenched you could have quenched he could have quenched we could have quenched you could have quenched they could have quenched
V-ing perfect
I could have been quenching you could have been quenching he could have been quenching we could have been quenching you could have been quenching they could have been quenching
Negation
Simple form
I could not quench you could not quench he could not quench we could not quench you could not quench they could not quench
V-ing form
I could not be quenching you could not be quenching he could not be quenching we could not be quenching you could not be quenching they could not be quenching
Perfect
I could not have quenched you could not have quenched he could not have quenched we could not have quenched you could not have quenched they could not have quenched
V-ing perfect
I could not have been quenching you could not have been quenching he could not have been quenching we could not have been quenching you could not have been quenching they could not have been quenching
Interrogative form
Simple form
could I quench? could you quench? could he quench? could we quench? could you quench? could they quench?
V-ing form
could I be quenching? could you be quenching? could he be quenching? could we be quenching? could you be quenching? could they be quenching?
Perfect
could I have quenched? could you have quenched? could he have quenched? could we have quenched? could you have quenched? could they have quenched?
V-ing perfect
could I have been quenching? could you have been quenching? could he have been quenching? could we have been quenching? could you have been quenching? could they have been quenching?
Interro-negative form
Simple form
could I not quench? could you not quench? could he not quench? could we not quench? could you not quench? could they not quench?
V-ing form
could I not be quenching? could you not be quenching? could he not be quenching? could we not be quenching? could you not be quenching? could they not be quenching?
Perfect
could I not have quenched? could you not have quenched? could he not have quenched? could we not have quenched? could you not have quenched? could they not have quenched?
V-ing perfect
could I not have been quenching? could you not have been quenching? could he not have been quenching? could we not have been quenching? could you not have been quenching? could they not have been quenching?