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 couldn't grin you couldn't grin he couldn't grin we couldn't grin you couldn't grin they couldn't grin	I couldn't be grinning you couldn't be grinning he couldn't be grinning we couldn't be grinning you couldn't be grinning they couldn't be grinning
Perfect	V-ing perfect
I couldn't have grinned you couldn't have grinned he couldn't have grinned we couldn't have grinned you couldn't have grinned they couldn't have grinned	I couldn't have been grinning you couldn't have been grinning he couldn't have been grinning we couldn't have been grinning you couldn't have been grinning they couldn't 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
couldn't I grin? couldn't you grin? couldn't he grin? couldn't we grin? couldn't you grin? couldn't they grin?	couldn't I be grinning? couldn't you be grinning? couldn't he be grinning? couldn't we be grinning? couldn't you be grinning? couldn't they be grinning?
Perfect	V-ing perfect
couldn't I have grinned? couldn't you have grinned? couldn't he have grinned? couldn't we have grinned? couldn't you have grinned? couldn't they have grinned?	couldn't I have been grinning? couldn't you have been grinning? couldn't he have been grinning? couldn't we have been grinning? couldn't you have been grinning? couldn't they have been grinning?