I can fence you can fence he can fence we can fence you can fence they can fence
V-ing form
I can be fencing you can be fencing he can be fencing we can be fencing you can be fencing they can be fencing
Perfect
I can have fenced you can have fenced he can have fenced we can have fenced you can have fenced they can have fenced
V-ing perfect
I can have been fencing you can have been fencing he can have been fencing we can have been fencing you can have been fencing they can have been fencing
Negation
Simple form
I cannot fence you cannot fence he cannot fence we cannot fence you cannot fence they cannot fence
V-ing form
I cannot be fencing you cannot be fencing he cannot be fencing we cannot be fencing you cannot be fencing they cannot be fencing
Perfect
I cannot have fenced you cannot have fenced he cannot have fenced we cannot have fenced you cannot have fenced they cannot have fenced
V-ing perfect
I cannot have been fencing you cannot have been fencing he cannot have been fencing we cannot have been fencing you cannot have been fencing they cannot have been fencing
Interrogative form
Simple form
can I fence? can you fence? can he fence? can we fence? can you fence? can they fence?
V-ing form
can I be fencing? can you be fencing? can he be fencing? can we be fencing? can you be fencing? can they be fencing?
Perfect
can I have fenced? can you have fenced? can he have fenced? can we have fenced? can you have fenced? can they have fenced?
V-ing perfect
can I have been fencing? can you have been fencing? can he have been fencing? can we have been fencing? can you have been fencing? can they have been fencing?
Interro-negative form
Simple form
can I not fence? can you not fence? can he not fence? can we not fence? can you not fence? can they not fence?
V-ing form
can I not be fencing? can you not be fencing? can he not be fencing? can we not be fencing? can you not be fencing? can they not be fencing?
Perfect
can I not have fenced? can you not have fenced? can he not have fenced? can we not have fenced? can you not have fenced? can they not have fenced?
V-ing perfect
can I not have been fencing? can you not have been fencing? can he not have been fencing? can we not have been fencing? can you not have been fencing? can they not have been fencing?