I could grimace you could grimace she could grimace we could grimace you could grimace they could grimace
V-ing form
I could be grimacing you could be grimacing she could be grimacing we could be grimacing you could be grimacing they could be grimacing
Perfect
I could have grimaced you could have grimaced she could have grimaced we could have grimaced you could have grimaced they could have grimaced
V-ing perfect
I could have been grimacing you could have been grimacing she could have been grimacing we could have been grimacing you could have been grimacing they could have been grimacing
Negation
Simple form
I couldn't grimace you couldn't grimace she couldn't grimace we couldn't grimace you couldn't grimace they couldn't grimace
V-ing form
I couldn't be grimacing you couldn't be grimacing she couldn't be grimacing we couldn't be grimacing you couldn't be grimacing they couldn't be grimacing
Perfect
I couldn't have grimaced you couldn't have grimaced she couldn't have grimaced we couldn't have grimaced you couldn't have grimaced they couldn't have grimaced
V-ing perfect
I couldn't have been grimacing you couldn't have been grimacing she couldn't have been grimacing we couldn't have been grimacing you couldn't have been grimacing they couldn't have been grimacing
Interrogative form
Simple form
could I grimace? could you grimace? could she grimace? could we grimace? could you grimace? could they grimace?
V-ing form
could I be grimacing? could you be grimacing? could she be grimacing? could we be grimacing? could you be grimacing? could they be grimacing?
Perfect
could I have grimaced? could you have grimaced? could she have grimaced? could we have grimaced? could you have grimaced? could they have grimaced?
V-ing perfect
could I have been grimacing? could you have been grimacing? could she have been grimacing? could we have been grimacing? could you have been grimacing? could they have been grimacing?
Interro-negative form
Simple form
couldn't I grimace? couldn't you grimace? couldn't she grimace? couldn't we grimace? couldn't you grimace? couldn't they grimace?
V-ing form
couldn't I be grimacing? couldn't you be grimacing? couldn't she be grimacing? couldn't we be grimacing? couldn't you be grimacing? couldn't they be grimacing?
Perfect
couldn't I have grimaced? couldn't you have grimaced? couldn't she have grimaced? couldn't we have grimaced? couldn't you have grimaced? couldn't they have grimaced?
V-ing perfect
couldn't I have been grimacing? couldn't you have been grimacing? couldn't she have been grimacing? couldn't we have been grimacing? couldn't you have been grimacing? couldn't they have been grimacing?