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 couldn't welter you couldn't welter he couldn't welter we couldn't welter you couldn't welter they couldn't welter
V-ing form
I couldn't be weltering you couldn't be weltering he couldn't be weltering we couldn't be weltering you couldn't be weltering they couldn't be weltering
Perfect
I couldn't have weltered you couldn't have weltered he couldn't have weltered we couldn't have weltered you couldn't have weltered they couldn't have weltered
V-ing perfect
I couldn't have been weltering you couldn't have been weltering he couldn't have been weltering we couldn't have been weltering you couldn't have been weltering they couldn't 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
couldn't I welter? couldn't you welter? couldn't he welter? couldn't we welter? couldn't you welter? couldn't they welter?
V-ing form
couldn't I be weltering? couldn't you be weltering? couldn't he be weltering? couldn't we be weltering? couldn't you be weltering? couldn't they be weltering?
Perfect
couldn't I have weltered? couldn't you have weltered? couldn't he have weltered? couldn't we have weltered? couldn't you have weltered? couldn't they have weltered?
V-ing perfect
couldn't I have been weltering? couldn't you have been weltering? couldn't he have been weltering? couldn't we have been weltering? couldn't you have been weltering? couldn't they have been weltering?