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 couldn't frustrate you couldn't frustrate he couldn't frustrate we couldn't frustrate you couldn't frustrate they couldn't frustrate
V-ing form
I couldn't be frustrating you couldn't be frustrating he couldn't be frustrating we couldn't be frustrating you couldn't be frustrating they couldn't be frustrating
Perfect
I couldn't have frustrated you couldn't have frustrated he couldn't have frustrated we couldn't have frustrated you couldn't have frustrated they couldn't have frustrated
V-ing perfect
I couldn't have been frustrating you couldn't have been frustrating he couldn't have been frustrating we couldn't have been frustrating you couldn't have been frustrating they couldn't 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
couldn't I frustrate? couldn't you frustrate? couldn't he frustrate? couldn't we frustrate? couldn't you frustrate? couldn't they frustrate?
V-ing form
couldn't I be frustrating? couldn't you be frustrating? couldn't he be frustrating? couldn't we be frustrating? couldn't you be frustrating? couldn't they be frustrating?
Perfect
couldn't I have frustrated? couldn't you have frustrated? couldn't he have frustrated? couldn't we have frustrated? couldn't you have frustrated? couldn't they have frustrated?
V-ing perfect
couldn't I have been frustrating? couldn't you have been frustrating? couldn't he have been frustrating? couldn't we have been frustrating? couldn't you have been frustrating? couldn't they have been frustrating?