I could vibrate you could vibrate she could vibrate we could vibrate you could vibrate they could vibrate
V-ing form
I could be vibrating you could be vibrating she could be vibrating we could be vibrating you could be vibrating they could be vibrating
Perfect
I could have vibrated you could have vibrated she could have vibrated we could have vibrated you could have vibrated they could have vibrated
V-ing perfect
I could have been vibrating you could have been vibrating she could have been vibrating we could have been vibrating you could have been vibrating they could have been vibrating
Negation
Simple form
I could not vibrate you could not vibrate she could not vibrate we could not vibrate you could not vibrate they could not vibrate
V-ing form
I could not be vibrating you could not be vibrating she could not be vibrating we could not be vibrating you could not be vibrating they could not be vibrating
Perfect
I could not have vibrated you could not have vibrated she could not have vibrated we could not have vibrated you could not have vibrated they could not have vibrated
V-ing perfect
I could not have been vibrating you could not have been vibrating she could not have been vibrating we could not have been vibrating you could not have been vibrating they could not have been vibrating
Interrogative form
Simple form
could I vibrate? could you vibrate? could she vibrate? could we vibrate? could you vibrate? could they vibrate?
V-ing form
could I be vibrating? could you be vibrating? could she be vibrating? could we be vibrating? could you be vibrating? could they be vibrating?
Perfect
could I have vibrated? could you have vibrated? could she have vibrated? could we have vibrated? could you have vibrated? could they have vibrated?
V-ing perfect
could I have been vibrating? could you have been vibrating? could she have been vibrating? could we have been vibrating? could you have been vibrating? could they have been vibrating?
Interro-negative form
Simple form
could I not vibrate? could you not vibrate? could she not vibrate? could we not vibrate? could you not vibrate? could they not vibrate?
V-ing form
could I not be vibrating? could you not be vibrating? could she not be vibrating? could we not be vibrating? could you not be vibrating? could they not be vibrating?
Perfect
could I not have vibrated? could you not have vibrated? could she not have vibrated? could we not have vibrated? could you not have vibrated? could they not have vibrated?
V-ing perfect
could I not have been vibrating? could you not have been vibrating? could she not have been vibrating? could we not have been vibrating? could you not have been vibrating? could they not have been vibrating?