English verb conjugation
COULD CLENCH

Regular verb: clench - clenched - clenched

Affirmation

Simple form	V-ing form
I could clench you could clench he could clench we could clench you could clench they could clench	I could be clenching you could be clenching he could be clenching we could be clenching you could be clenching they could be clenching
Perfect	V-ing perfect
I could have clenched you could have clenched he could have clenched we could have clenched you could have clenched they could have clenched	I could have been clenching you could have been clenching he could have been clenching we could have been clenching you could have been clenching they could have been clenching

Negation

Simple form	V-ing form
I couldn't clench you couldn't clench he couldn't clench we couldn't clench you couldn't clench they couldn't clench	I couldn't be clenching you couldn't be clenching he couldn't be clenching we couldn't be clenching you couldn't be clenching they couldn't be clenching
Perfect	V-ing perfect
I couldn't have clenched you couldn't have clenched he couldn't have clenched we couldn't have clenched you couldn't have clenched they couldn't have clenched	I couldn't have been clenching you couldn't have been clenching he couldn't have been clenching we couldn't have been clenching you couldn't have been clenching they couldn't have been clenching

Interrogative form

Simple form	V-ing form
could I clench? could you clench? could he clench? could we clench? could you clench? could they clench?	could I be clenching? could you be clenching? could he be clenching? could we be clenching? could you be clenching? could they be clenching?
Perfect	V-ing perfect
could I have clenched? could you have clenched? could he have clenched? could we have clenched? could you have clenched? could they have clenched?	could I have been clenching? could you have been clenching? could he have been clenching? could we have been clenching? could you have been clenching? could they have been clenching?

Interro-negative form

Simple form	V-ing form
couldn't I clench? couldn't you clench? couldn't he clench? couldn't we clench? couldn't you clench? couldn't they clench?	couldn't I be clenching? couldn't you be clenching? couldn't he be clenching? couldn't we be clenching? couldn't you be clenching? couldn't they be clenching?
Perfect	V-ing perfect
couldn't I have clenched? couldn't you have clenched? couldn't he have clenched? couldn't we have clenched? couldn't you have clenched? couldn't they have clenched?	couldn't I have been clenching? couldn't you have been clenching? couldn't he have been clenching? couldn't we have been clenching? couldn't you have been clenching? couldn't they have been clenching?