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