I can swallow you can swallow he can swallow we can swallow you can swallow they can swallow
V-ing form
I can be swallowing you can be swallowing he can be swallowing we can be swallowing you can be swallowing they can be swallowing
Perfect
I can have swallowed you can have swallowed he can have swallowed we can have swallowed you can have swallowed they can have swallowed
V-ing perfect
I can have been swallowing you can have been swallowing he can have been swallowing we can have been swallowing you can have been swallowing they can have been swallowing
Negation
Simple form
I cannot swallow you cannot swallow he cannot swallow we cannot swallow you cannot swallow they cannot swallow
V-ing form
I cannot be swallowing you cannot be swallowing he cannot be swallowing we cannot be swallowing you cannot be swallowing they cannot be swallowing
Perfect
I cannot have swallowed you cannot have swallowed he cannot have swallowed we cannot have swallowed you cannot have swallowed they cannot have swallowed
V-ing perfect
I cannot have been swallowing you cannot have been swallowing he cannot have been swallowing we cannot have been swallowing you cannot have been swallowing they cannot have been swallowing
Interrogative form
Simple form
can I swallow? can you swallow? can he swallow? can we swallow? can you swallow? can they swallow?
V-ing form
can I be swallowing? can you be swallowing? can he be swallowing? can we be swallowing? can you be swallowing? can they be swallowing?
Perfect
can I have swallowed? can you have swallowed? can he have swallowed? can we have swallowed? can you have swallowed? can they have swallowed?
V-ing perfect
can I have been swallowing? can you have been swallowing? can he have been swallowing? can we have been swallowing? can you have been swallowing? can they have been swallowing?
Interro-negative form
Simple form
can I not swallow? can you not swallow? can he not swallow? can we not swallow? can you not swallow? can they not swallow?
V-ing form
can I not be swallowing? can you not be swallowing? can he not be swallowing? can we not be swallowing? can you not be swallowing? can they not be swallowing?
Perfect
can I not have swallowed? can you not have swallowed? can he not have swallowed? can we not have swallowed? can you not have swallowed? can they not have swallowed?
V-ing perfect
can I not have been swallowing? can you not have been swallowing? can he not have been swallowing? can we not have been swallowing? can you not have been swallowing? can they not have been swallowing?