English verb conjugation
COULD BIRCH

Regular verb: birch - birched - birched

Affirmation

Simple form	V-ing form
I could birch you could birch he could birch we could birch you could birch they could birch	I could be birching you could be birching he could be birching we could be birching you could be birching they could be birching
Perfect	V-ing perfect
I could have birched you could have birched he could have birched we could have birched you could have birched they could have birched	I could have been birching you could have been birching he could have been birching we could have been birching you could have been birching they could have been birching

Negation

Simple form	V-ing form
I couldn't birch you couldn't birch he couldn't birch we couldn't birch you couldn't birch they couldn't birch	I couldn't be birching you couldn't be birching he couldn't be birching we couldn't be birching you couldn't be birching they couldn't be birching
Perfect	V-ing perfect
I couldn't have birched you couldn't have birched he couldn't have birched we couldn't have birched you couldn't have birched they couldn't have birched	I couldn't have been birching you couldn't have been birching he couldn't have been birching we couldn't have been birching you couldn't have been birching they couldn't have been birching

Interrogative form

Simple form	V-ing form
could I birch? could you birch? could he birch? could we birch? could you birch? could they birch?	could I be birching? could you be birching? could he be birching? could we be birching? could you be birching? could they be birching?
Perfect	V-ing perfect
could I have birched? could you have birched? could he have birched? could we have birched? could you have birched? could they have birched?	could I have been birching? could you have been birching? could he have been birching? could we have been birching? could you have been birching? could they have been birching?

Interro-negative form

Simple form	V-ing form
couldn't I birch? couldn't you birch? couldn't he birch? couldn't we birch? couldn't you birch? couldn't they birch?	couldn't I be birching? couldn't you be birching? couldn't he be birching? couldn't we be birching? couldn't you be birching? couldn't they be birching?
Perfect	V-ing perfect
couldn't I have birched? couldn't you have birched? couldn't he have birched? couldn't we have birched? couldn't you have birched? couldn't they have birched?	couldn't I have been birching? couldn't you have been birching? couldn't he have been birching? couldn't we have been birching? couldn't you have been birching? couldn't they have been birching?