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 couldn't clump you couldn't clump he couldn't clump we couldn't clump you couldn't clump they couldn't clump
V-ing form
I couldn't be clumping you couldn't be clumping he couldn't be clumping we couldn't be clumping you couldn't be clumping they couldn't be clumping
Perfect
I couldn't have clumped you couldn't have clumped he couldn't have clumped we couldn't have clumped you couldn't have clumped they couldn't have clumped
V-ing perfect
I couldn't have been clumping you couldn't have been clumping he couldn't have been clumping we couldn't have been clumping you couldn't have been clumping they couldn't 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
couldn't I clump? couldn't you clump? couldn't he clump? couldn't we clump? couldn't you clump? couldn't they clump?
V-ing form
couldn't I be clumping? couldn't you be clumping? couldn't he be clumping? couldn't we be clumping? couldn't you be clumping? couldn't they be clumping?
Perfect
couldn't I have clumped? couldn't you have clumped? couldn't he have clumped? couldn't we have clumped? couldn't you have clumped? couldn't they have clumped?
V-ing perfect
couldn't I have been clumping? couldn't you have been clumping? couldn't he have been clumping? couldn't we have been clumping? couldn't you have been clumping? couldn't they have been clumping?