English verb conjugation
COULD KNIFE

Regular verb: knife - knifed - knifed

Affirmation

Simple form	V-ing form
I could knife you could knife she could knife we could knife you could knife they could knife	I could be knifing you could be knifing she could be knifing we could be knifing you could be knifing they could be knifing
Perfect	V-ing perfect
I could have knifed you could have knifed she could have knifed we could have knifed you could have knifed they could have knifed	I could have been knifing you could have been knifing she could have been knifing we could have been knifing you could have been knifing they could have been knifing

Negation

Simple form	V-ing form
I couldn't knife you couldn't knife she couldn't knife we couldn't knife you couldn't knife they couldn't knife	I couldn't be knifing you couldn't be knifing she couldn't be knifing we couldn't be knifing you couldn't be knifing they couldn't be knifing
Perfect	V-ing perfect
I couldn't have knifed you couldn't have knifed she couldn't have knifed we couldn't have knifed you couldn't have knifed they couldn't have knifed	I couldn't have been knifing you couldn't have been knifing she couldn't have been knifing we couldn't have been knifing you couldn't have been knifing they couldn't have been knifing

Interrogative form

Simple form	V-ing form
could I knife? could you knife? could she knife? could we knife? could you knife? could they knife?	could I be knifing? could you be knifing? could she be knifing? could we be knifing? could you be knifing? could they be knifing?
Perfect	V-ing perfect
could I have knifed? could you have knifed? could she have knifed? could we have knifed? could you have knifed? could they have knifed?	could I have been knifing? could you have been knifing? could she have been knifing? could we have been knifing? could you have been knifing? could they have been knifing?

Interro-negative form

Simple form	V-ing form
couldn't I knife? couldn't you knife? couldn't she knife? couldn't we knife? couldn't you knife? couldn't they knife?	couldn't I be knifing? couldn't you be knifing? couldn't she be knifing? couldn't we be knifing? couldn't you be knifing? couldn't they be knifing?
Perfect	V-ing perfect
couldn't I have knifed? couldn't you have knifed? couldn't she have knifed? couldn't we have knifed? couldn't you have knifed? couldn't they have knifed?	couldn't I have been knifing? couldn't you have been knifing? couldn't she have been knifing? couldn't we have been knifing? couldn't you have been knifing? couldn't they have been knifing?