English verb conjugation
COULD AUTHENTICATE

Regular verb: authenticate - authenticated - authenticated

Affirmation

Simple form	V-ing form
I could authenticate you could authenticate he could authenticate we could authenticate you could authenticate they could authenticate	I could be authenticating you could be authenticating he could be authenticating we could be authenticating you could be authenticating they could be authenticating
Perfect	V-ing perfect
I could have authenticated you could have authenticated he could have authenticated we could have authenticated you could have authenticated they could have authenticated	I could have been authenticating you could have been authenticating he could have been authenticating we could have been authenticating you could have been authenticating they could have been authenticating

Negation

Simple form	V-ing form
I couldn't authenticate you couldn't authenticate he couldn't authenticate we couldn't authenticate you couldn't authenticate they couldn't authenticate	I couldn't be authenticating you couldn't be authenticating he couldn't be authenticating we couldn't be authenticating you couldn't be authenticating they couldn't be authenticating
Perfect	V-ing perfect
I couldn't have authenticated you couldn't have authenticated he couldn't have authenticated we couldn't have authenticated you couldn't have authenticated they couldn't have authenticated	I couldn't have been authenticating you couldn't have been authenticating he couldn't have been authenticating we couldn't have been authenticating you couldn't have been authenticating they couldn't have been authenticating

Interrogative form

Simple form	V-ing form
could I authenticate? could you authenticate? could he authenticate? could we authenticate? could you authenticate? could they authenticate?	could I be authenticating? could you be authenticating? could he be authenticating? could we be authenticating? could you be authenticating? could they be authenticating?
Perfect	V-ing perfect
could I have authenticated? could you have authenticated? could he have authenticated? could we have authenticated? could you have authenticated? could they have authenticated?	could I have been authenticating? could you have been authenticating? could he have been authenticating? could we have been authenticating? could you have been authenticating? could they have been authenticating?

Interro-negative form

Simple form	V-ing form
couldn't I authenticate? couldn't you authenticate? couldn't he authenticate? couldn't we authenticate? couldn't you authenticate? couldn't they authenticate?	couldn't I be authenticating? couldn't you be authenticating? couldn't he be authenticating? couldn't we be authenticating? couldn't you be authenticating? couldn't they be authenticating?
Perfect	V-ing perfect
couldn't I have authenticated? couldn't you have authenticated? couldn't he have authenticated? couldn't we have authenticated? couldn't you have authenticated? couldn't they have authenticated?	couldn't I have been authenticating? couldn't you have been authenticating? couldn't he have been authenticating? couldn't we have been authenticating? couldn't you have been authenticating? couldn't they have been authenticating?