I could frustrate you could frustrate he could frustrate we could frustrate you could frustrate they could frustrate
V-ing form
I could be frustrating you could be frustrating he could be frustrating we could be frustrating you could be frustrating they could be frustrating
Perfect
I could have frustrated you could have frustrated he could have frustrated we could have frustrated you could have frustrated they could have frustrated
V-ing perfect
I could have been frustrating you could have been frustrating he could have been frustrating we could have been frustrating you could have been frustrating they could have been frustrating
Negation
Simple form
I could not frustrate you could not frustrate he could not frustrate we could not frustrate you could not frustrate they could not frustrate
V-ing form
I could not be frustrating you could not be frustrating he could not be frustrating we could not be frustrating you could not be frustrating they could not be frustrating
Perfect
I could not have frustrated you could not have frustrated he could not have frustrated we could not have frustrated you could not have frustrated they could not have frustrated
V-ing perfect
I could not have been frustrating you could not have been frustrating he could not have been frustrating we could not have been frustrating you could not have been frustrating they could not have been frustrating
Interrogative form
Simple form
could I frustrate? could you frustrate? could he frustrate? could we frustrate? could you frustrate? could they frustrate?
V-ing form
could I be frustrating? could you be frustrating? could he be frustrating? could we be frustrating? could you be frustrating? could they be frustrating?
Perfect
could I have frustrated? could you have frustrated? could he have frustrated? could we have frustrated? could you have frustrated? could they have frustrated?
V-ing perfect
could I have been frustrating? could you have been frustrating? could he have been frustrating? could we have been frustrating? could you have been frustrating? could they have been frustrating?
Interro-negative form
Simple form
could I not frustrate? could you not frustrate? could he not frustrate? could we not frustrate? could you not frustrate? could they not frustrate?
V-ing form
could I not be frustrating? could you not be frustrating? could he not be frustrating? could we not be frustrating? could you not be frustrating? could they not be frustrating?
Perfect
could I not have frustrated? could you not have frustrated? could he not have frustrated? could we not have frustrated? could you not have frustrated? could they not have frustrated?
V-ing perfect
could I not have been frustrating? could you not have been frustrating? could he not have been frustrating? could we not have been frustrating? could you not have been frustrating? could they not have been frustrating?