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