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