I could authenticate you could authenticate he could authenticate we could authenticate you could authenticate they could authenticate
V-ing form
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
I could have authenticated you could have authenticated he could have authenticated we could have authenticated you could have authenticated they could have authenticated
V-ing perfect
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
I could not authenticate you could not authenticate he could not authenticate we could not authenticate you could not authenticate they could not authenticate
V-ing form
I could not be authenticating you could not be authenticating he could not be authenticating we could not be authenticating you could not be authenticating they could not be authenticating
Perfect
I could not have authenticated you could not have authenticated he could not have authenticated we could not have authenticated you could not have authenticated they could not have authenticated
V-ing perfect
I could not have been authenticating you could not have been authenticating he could not have been authenticating we could not have been authenticating you could not have been authenticating they could not have been authenticating
Interrogative form
Simple form
could I authenticate? could you authenticate? could he authenticate? could we authenticate? could you authenticate? could they authenticate?
V-ing form
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
could I have authenticated? could you have authenticated? could he have authenticated? could we have authenticated? could you have authenticated? could they have authenticated?
V-ing perfect
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
could I not authenticate? could you not authenticate? could he not authenticate? could we not authenticate? could you not authenticate? could they not authenticate?
V-ing form
could I not be authenticating? could you not be authenticating? could he not be authenticating? could we not be authenticating? could you not be authenticating? could they not be authenticating?
Perfect
could I not have authenticated? could you not have authenticated? could he not have authenticated? could we not have authenticated? could you not have authenticated? could they not have authenticated?
V-ing perfect
could I not have been authenticating? could you not have been authenticating? could he not have been authenticating? could we not have been authenticating? could you not have been authenticating? could they not have been authenticating?