English verb conjugation
COULD BIRL

Regular verb: birl - birled - birled

Affirmation

Simple form	V-ing form
I could birl you could birl she could birl we could birl you could birl they could birl	I could be birling you could be birling she could be birling we could be birling you could be birling they could be birling
Perfect	V-ing perfect
I could have birled you could have birled she could have birled we could have birled you could have birled they could have birled	I could have been birling you could have been birling she could have been birling we could have been birling you could have been birling they could have been birling

Negation

Simple form	V-ing form
I couldn't birl you couldn't birl she couldn't birl we couldn't birl you couldn't birl they couldn't birl	I couldn't be birling you couldn't be birling she couldn't be birling we couldn't be birling you couldn't be birling they couldn't be birling
Perfect	V-ing perfect
I couldn't have birled you couldn't have birled she couldn't have birled we couldn't have birled you couldn't have birled they couldn't have birled	I couldn't have been birling you couldn't have been birling she couldn't have been birling we couldn't have been birling you couldn't have been birling they couldn't have been birling

Interrogative form

Simple form	V-ing form
could I birl? could you birl? could she birl? could we birl? could you birl? could they birl?	could I be birling? could you be birling? could she be birling? could we be birling? could you be birling? could they be birling?
Perfect	V-ing perfect
could I have birled? could you have birled? could she have birled? could we have birled? could you have birled? could they have birled?	could I have been birling? could you have been birling? could she have been birling? could we have been birling? could you have been birling? could they have been birling?

Interro-negative form

Simple form	V-ing form
couldn't I birl? couldn't you birl? couldn't she birl? couldn't we birl? couldn't you birl? couldn't they birl?	couldn't I be birling? couldn't you be birling? couldn't she be birling? couldn't we be birling? couldn't you be birling? couldn't they be birling?
Perfect	V-ing perfect
couldn't I have birled? couldn't you have birled? couldn't she have birled? couldn't we have birled? couldn't you have birled? couldn't they have birled?	couldn't I have been birling? couldn't you have been birling? couldn't she have been birling? couldn't we have been birling? couldn't you have been birling? couldn't they have been birling?