English verb conjugation
COULD GRIN

Regular verb: grin - grinned - grinned

Affirmation

Simple form	V-ing form
I could grin you could grin he could grin we could grin you could grin they could grin	I could be grinning you could be grinning he could be grinning we could be grinning you could be grinning they could be grinning
Perfect	V-ing perfect
I could have grinned you could have grinned he could have grinned we could have grinned you could have grinned they could have grinned	I could have been grinning you could have been grinning he could have been grinning we could have been grinning you could have been grinning they could have been grinning

Negation

Simple form	V-ing form
I could not grin you could not grin he could not grin we could not grin you could not grin they could not grin	I could not be grinning you could not be grinning he could not be grinning we could not be grinning you could not be grinning they could not be grinning
Perfect	V-ing perfect
I could not have grinned you could not have grinned he could not have grinned we could not have grinned you could not have grinned they could not have grinned	I could not have been grinning you could not have been grinning he could not have been grinning we could not have been grinning you could not have been grinning they could not have been grinning

Interrogative form

Simple form	V-ing form
could I grin? could you grin? could he grin? could we grin? could you grin? could they grin?	could I be grinning? could you be grinning? could he be grinning? could we be grinning? could you be grinning? could they be grinning?
Perfect	V-ing perfect
could I have grinned? could you have grinned? could he have grinned? could we have grinned? could you have grinned? could they have grinned?	could I have been grinning? could you have been grinning? could he have been grinning? could we have been grinning? could you have been grinning? could they have been grinning?

Interro-negative form

Simple form	V-ing form
could I not grin? could you not grin? could he not grin? could we not grin? could you not grin? could they not grin?	could I not be grinning? could you not be grinning? could he not be grinning? could we not be grinning? could you not be grinning? could they not be grinning?
Perfect	V-ing perfect
could I not have grinned? could you not have grinned? could he not have grinned? could we not have grinned? could you not have grinned? could they not have grinned?	could I not have been grinning? could you not have been grinning? could he not have been grinning? could we not have been grinning? could you not have been grinning? could they not have been grinning?