I could clump you could clump he could clump we could clump you could clump they could clump
V-ing form
I could be clumping you could be clumping he could be clumping we could be clumping you could be clumping they could be clumping
Perfect
I could have clumped you could have clumped he could have clumped we could have clumped you could have clumped they could have clumped
V-ing perfect
I could have been clumping you could have been clumping he could have been clumping we could have been clumping you could have been clumping they could have been clumping
Negation
Simple form
I could not clump you could not clump he could not clump we could not clump you could not clump they could not clump
V-ing form
I could not be clumping you could not be clumping he could not be clumping we could not be clumping you could not be clumping they could not be clumping
Perfect
I could not have clumped you could not have clumped he could not have clumped we could not have clumped you could not have clumped they could not have clumped
V-ing perfect
I could not have been clumping you could not have been clumping he could not have been clumping we could not have been clumping you could not have been clumping they could not have been clumping
Interrogative form
Simple form
could I clump? could you clump? could he clump? could we clump? could you clump? could they clump?
V-ing form
could I be clumping? could you be clumping? could he be clumping? could we be clumping? could you be clumping? could they be clumping?
Perfect
could I have clumped? could you have clumped? could he have clumped? could we have clumped? could you have clumped? could they have clumped?
V-ing perfect
could I have been clumping? could you have been clumping? could he have been clumping? could we have been clumping? could you have been clumping? could they have been clumping?
Interro-negative form
Simple form
could I not clump? could you not clump? could he not clump? could we not clump? could you not clump? could they not clump?
V-ing form
could I not be clumping? could you not be clumping? could he not be clumping? could we not be clumping? could you not be clumping? could they not be clumping?
Perfect
could I not have clumped? could you not have clumped? could he not have clumped? could we not have clumped? could you not have clumped? could they not have clumped?
V-ing perfect
could I not have been clumping? could you not have been clumping? could he not have been clumping? could we not have been clumping? could you not have been clumping? could they not have been clumping?