I can nibble you can nibble he can nibble we can nibble you can nibble they can nibble
V-ing form
I can be nibbling you can be nibbling he can be nibbling we can be nibbling you can be nibbling they can be nibbling
Perfect
I can have nibbled you can have nibbled he can have nibbled we can have nibbled you can have nibbled they can have nibbled
V-ing perfect
I can have been nibbling you can have been nibbling he can have been nibbling we can have been nibbling you can have been nibbling they can have been nibbling
Negation
Simple form
I cannot nibble you cannot nibble he cannot nibble we cannot nibble you cannot nibble they cannot nibble
V-ing form
I cannot be nibbling you cannot be nibbling he cannot be nibbling we cannot be nibbling you cannot be nibbling they cannot be nibbling
Perfect
I cannot have nibbled you cannot have nibbled he cannot have nibbled we cannot have nibbled you cannot have nibbled they cannot have nibbled
V-ing perfect
I cannot have been nibbling you cannot have been nibbling he cannot have been nibbling we cannot have been nibbling you cannot have been nibbling they cannot have been nibbling
Interrogative form
Simple form
can I nibble? can you nibble? can he nibble? can we nibble? can you nibble? can they nibble?
V-ing form
can I be nibbling? can you be nibbling? can he be nibbling? can we be nibbling? can you be nibbling? can they be nibbling?
Perfect
can I have nibbled? can you have nibbled? can he have nibbled? can we have nibbled? can you have nibbled? can they have nibbled?
V-ing perfect
can I have been nibbling? can you have been nibbling? can he have been nibbling? can we have been nibbling? can you have been nibbling? can they have been nibbling?
Interro-negative form
Simple form
can I not nibble? can you not nibble? can he not nibble? can we not nibble? can you not nibble? can they not nibble?
V-ing form
can I not be nibbling? can you not be nibbling? can he not be nibbling? can we not be nibbling? can you not be nibbling? can they not be nibbling?
Perfect
can I not have nibbled? can you not have nibbled? can he not have nibbled? can we not have nibbled? can you not have nibbled? can they not have nibbled?
V-ing perfect
can I not have been nibbling? can you not have been nibbling? can he not have been nibbling? can we not have been nibbling? can you not have been nibbling? can they not have been nibbling?