I could pay you could pay he could pay we could pay you could pay they could pay
V-ing form
I could be paying you could be paying he could be paying we could be paying you could be paying they could be paying
Perfect
I could have paid you could have paid he could have paid we could have paid you could have paid they could have paid
V-ing perfect
I could have been paying you could have been paying he could have been paying we could have been paying you could have been paying they could have been paying
Negation
Simple form
I couldn't pay you couldn't pay he couldn't pay we couldn't pay you couldn't pay they couldn't pay
V-ing form
I couldn't be paying you couldn't be paying he couldn't be paying we couldn't be paying you couldn't be paying they couldn't be paying
Perfect
I couldn't have paid you couldn't have paid he couldn't have paid we couldn't have paid you couldn't have paid they couldn't have paid
V-ing perfect
I couldn't have been paying you couldn't have been paying he couldn't have been paying we couldn't have been paying you couldn't have been paying they couldn't have been paying
Interrogative form
Simple form
could I pay? could you pay? could he pay? could we pay? could you pay? could they pay?
V-ing form
could I be paying? could you be paying? could he be paying? could we be paying? could you be paying? could they be paying?
Perfect
could I have paid? could you have paid? could he have paid? could we have paid? could you have paid? could they have paid?
V-ing perfect
could I have been paying? could you have been paying? could he have been paying? could we have been paying? could you have been paying? could they have been paying?
Interro-negative form
Simple form
couldn't I pay? couldn't you pay? couldn't he pay? couldn't we pay? couldn't you pay? couldn't they pay?
V-ing form
couldn't I be paying? couldn't you be paying? couldn't he be paying? couldn't we be paying? couldn't you be paying? couldn't they be paying?
Perfect
couldn't I have paid? couldn't you have paid? couldn't he have paid? couldn't we have paid? couldn't you have paid? couldn't they have paid?
V-ing perfect
couldn't I have been paying? couldn't you have been paying? couldn't he have been paying? couldn't we have been paying? couldn't you have been paying? couldn't they have been paying?