I could chew you could chew he could chew we could chew you could chew they could chew
V-ing form
I could be chewing you could be chewing he could be chewing we could be chewing you could be chewing they could be chewing
Perfect
I could have chewed you could have chewed he could have chewed we could have chewed you could have chewed they could have chewed
V-ing perfect
I could have been chewing you could have been chewing he could have been chewing we could have been chewing you could have been chewing they could have been chewing
Negation
Simple form
I could not chew you could not chew he could not chew we could not chew you could not chew they could not chew
V-ing form
I could not be chewing you could not be chewing he could not be chewing we could not be chewing you could not be chewing they could not be chewing
Perfect
I could not have chewed you could not have chewed he could not have chewed we could not have chewed you could not have chewed they could not have chewed
V-ing perfect
I could not have been chewing you could not have been chewing he could not have been chewing we could not have been chewing you could not have been chewing they could not have been chewing
Interrogative form
Simple form
could I chew? could you chew? could he chew? could we chew? could you chew? could they chew?
V-ing form
could I be chewing? could you be chewing? could he be chewing? could we be chewing? could you be chewing? could they be chewing?
Perfect
could I have chewed? could you have chewed? could he have chewed? could we have chewed? could you have chewed? could they have chewed?
V-ing perfect
could I have been chewing? could you have been chewing? could he have been chewing? could we have been chewing? could you have been chewing? could they have been chewing?
Interro-negative form
Simple form
could I not chew? could you not chew? could he not chew? could we not chew? could you not chew? could they not chew?
V-ing form
could I not be chewing? could you not be chewing? could he not be chewing? could we not be chewing? could you not be chewing? could they not be chewing?
Perfect
could I not have chewed? could you not have chewed? could he not have chewed? could we not have chewed? could you not have chewed? could they not have chewed?
V-ing perfect
could I not have been chewing? could you not have been chewing? could he not have been chewing? could we not have been chewing? could you not have been chewing? could they not have been chewing?