I could welter you could welter he could welter we could welter you could welter they could welter
V-ing form
I could be weltering you could be weltering he could be weltering we could be weltering you could be weltering they could be weltering
Perfect
I could have weltered you could have weltered he could have weltered we could have weltered you could have weltered they could have weltered
V-ing perfect
I could have been weltering you could have been weltering he could have been weltering we could have been weltering you could have been weltering they could have been weltering
Negation
Simple form
I could not welter you could not welter he could not welter we could not welter you could not welter they could not welter
V-ing form
I could not be weltering you could not be weltering he could not be weltering we could not be weltering you could not be weltering they could not be weltering
Perfect
I could not have weltered you could not have weltered he could not have weltered we could not have weltered you could not have weltered they could not have weltered
V-ing perfect
I could not have been weltering you could not have been weltering he could not have been weltering we could not have been weltering you could not have been weltering they could not have been weltering
Interrogative form
Simple form
could I welter? could you welter? could he welter? could we welter? could you welter? could they welter?
V-ing form
could I be weltering? could you be weltering? could he be weltering? could we be weltering? could you be weltering? could they be weltering?
Perfect
could I have weltered? could you have weltered? could he have weltered? could we have weltered? could you have weltered? could they have weltered?
V-ing perfect
could I have been weltering? could you have been weltering? could he have been weltering? could we have been weltering? could you have been weltering? could they have been weltering?
Interro-negative form
Simple form
could I not welter? could you not welter? could he not welter? could we not welter? could you not welter? could they not welter?
V-ing form
could I not be weltering? could you not be weltering? could he not be weltering? could we not be weltering? could you not be weltering? could they not be weltering?
Perfect
could I not have weltered? could you not have weltered? could he not have weltered? could we not have weltered? could you not have weltered? could they not have weltered?
V-ing perfect
could I not have been weltering? could you not have been weltering? could he not have been weltering? could we not have been weltering? could you not have been weltering? could they not have been weltering?