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 couldn't quench you couldn't quench he couldn't quench we couldn't quench you couldn't quench they couldn't quench
V-ing form
I couldn't be quenching you couldn't be quenching he couldn't be quenching we couldn't be quenching you couldn't be quenching they couldn't be quenching
Perfect
I couldn't have quenched you couldn't have quenched he couldn't have quenched we couldn't have quenched you couldn't have quenched they couldn't have quenched
V-ing perfect
I couldn't have been quenching you couldn't have been quenching he couldn't have been quenching we couldn't have been quenching you couldn't have been quenching they couldn't 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
couldn't I quench? couldn't you quench? couldn't he quench? couldn't we quench? couldn't you quench? couldn't they quench?
V-ing form
couldn't I be quenching? couldn't you be quenching? couldn't he be quenching? couldn't we be quenching? couldn't you be quenching? couldn't they be quenching?
Perfect
couldn't I have quenched? couldn't you have quenched? couldn't he have quenched? couldn't we have quenched? couldn't you have quenched? couldn't they have quenched?
V-ing perfect
couldn't I have been quenching? couldn't you have been quenching? couldn't he have been quenching? couldn't we have been quenching? couldn't you have been quenching? couldn't they have been quenching?