I can tub you can tub she can tub we can tub you can tub they can tub
V-ing form
I can be tubbing you can be tubbing she can be tubbing we can be tubbing you can be tubbing they can be tubbing
Perfect
I can have tubbed you can have tubbed she can have tubbed we can have tubbed you can have tubbed they can have tubbed
V-ing perfect
I can have been tubbing you can have been tubbing she can have been tubbing we can have been tubbing you can have been tubbing they can have been tubbing
Negation
Simple form
I cannot tub you cannot tub she cannot tub we cannot tub you cannot tub they cannot tub
V-ing form
I cannot be tubbing you cannot be tubbing she cannot be tubbing we cannot be tubbing you cannot be tubbing they cannot be tubbing
Perfect
I cannot have tubbed you cannot have tubbed she cannot have tubbed we cannot have tubbed you cannot have tubbed they cannot have tubbed
V-ing perfect
I cannot have been tubbing you cannot have been tubbing she cannot have been tubbing we cannot have been tubbing you cannot have been tubbing they cannot have been tubbing
Interrogative form
Simple form
can I tub? can you tub? can she tub? can we tub? can you tub? can they tub?
V-ing form
can I be tubbing? can you be tubbing? can she be tubbing? can we be tubbing? can you be tubbing? can they be tubbing?
Perfect
can I have tubbed? can you have tubbed? can she have tubbed? can we have tubbed? can you have tubbed? can they have tubbed?
V-ing perfect
can I have been tubbing? can you have been tubbing? can she have been tubbing? can we have been tubbing? can you have been tubbing? can they have been tubbing?
Interro-negative form
Simple form
can I not tub? can you not tub? can she not tub? can we not tub? can you not tub? can they not tub?
V-ing form
can I not be tubbing? can you not be tubbing? can she not be tubbing? can we not be tubbing? can you not be tubbing? can they not be tubbing?
Perfect
can I not have tubbed? can you not have tubbed? can she not have tubbed? can we not have tubbed? can you not have tubbed? can they not have tubbed?
V-ing perfect
can I not have been tubbing? can you not have been tubbing? can she not have been tubbing? can we not have been tubbing? can you not have been tubbing? can they not have been tubbing?