I can fasten you can fasten she can fasten we can fasten you can fasten they can fasten
V-ing form
I can be fastening you can be fastening she can be fastening we can be fastening you can be fastening they can be fastening
Perfect
I can have fastened you can have fastened she can have fastened we can have fastened you can have fastened they can have fastened
V-ing perfect
I can have been fastening you can have been fastening she can have been fastening we can have been fastening you can have been fastening they can have been fastening
Negation
Simple form
I cannot fasten you cannot fasten she cannot fasten we cannot fasten you cannot fasten they cannot fasten
V-ing form
I cannot be fastening you cannot be fastening she cannot be fastening we cannot be fastening you cannot be fastening they cannot be fastening
Perfect
I cannot have fastened you cannot have fastened she cannot have fastened we cannot have fastened you cannot have fastened they cannot have fastened
V-ing perfect
I cannot have been fastening you cannot have been fastening she cannot have been fastening we cannot have been fastening you cannot have been fastening they cannot have been fastening
Interrogative form
Simple form
can I fasten? can you fasten? can she fasten? can we fasten? can you fasten? can they fasten?
V-ing form
can I be fastening? can you be fastening? can she be fastening? can we be fastening? can you be fastening? can they be fastening?
Perfect
can I have fastened? can you have fastened? can she have fastened? can we have fastened? can you have fastened? can they have fastened?
V-ing perfect
can I have been fastening? can you have been fastening? can she have been fastening? can we have been fastening? can you have been fastening? can they have been fastening?
Interro-negative form
Simple form
can I not fasten? can you not fasten? can she not fasten? can we not fasten? can you not fasten? can they not fasten?
V-ing form
can I not be fastening? can you not be fastening? can she not be fastening? can we not be fastening? can you not be fastening? can they not be fastening?
Perfect
can I not have fastened? can you not have fastened? can she not have fastened? can we not have fastened? can you not have fastened? can they not have fastened?
V-ing perfect
can I not have been fastening? can you not have been fastening? can she not have been fastening? can we not have been fastening? can you not have been fastening? can they not have been fastening?