I can smoke you can smoke he can smoke we can smoke you can smoke they can smoke
V-ing form
I can be smoking you can be smoking he can be smoking we can be smoking you can be smoking they can be smoking
Perfect
I can have smoked you can have smoked he can have smoked we can have smoked you can have smoked they can have smoked
V-ing perfect
I can have been smoking you can have been smoking he can have been smoking we can have been smoking you can have been smoking they can have been smoking
Negation
Simple form
I cannot smoke you cannot smoke he cannot smoke we cannot smoke you cannot smoke they cannot smoke
V-ing form
I cannot be smoking you cannot be smoking he cannot be smoking we cannot be smoking you cannot be smoking they cannot be smoking
Perfect
I cannot have smoked you cannot have smoked he cannot have smoked we cannot have smoked you cannot have smoked they cannot have smoked
V-ing perfect
I cannot have been smoking you cannot have been smoking he cannot have been smoking we cannot have been smoking you cannot have been smoking they cannot have been smoking
Interrogative form
Simple form
can I smoke? can you smoke? can he smoke? can we smoke? can you smoke? can they smoke?
V-ing form
can I be smoking? can you be smoking? can he be smoking? can we be smoking? can you be smoking? can they be smoking?
Perfect
can I have smoked? can you have smoked? can he have smoked? can we have smoked? can you have smoked? can they have smoked?
V-ing perfect
can I have been smoking? can you have been smoking? can he have been smoking? can we have been smoking? can you have been smoking? can they have been smoking?
Interro-negative form
Simple form
can I not smoke? can you not smoke? can he not smoke? can we not smoke? can you not smoke? can they not smoke?
V-ing form
can I not be smoking? can you not be smoking? can he not be smoking? can we not be smoking? can you not be smoking? can they not be smoking?
Perfect
can I not have smoked? can you not have smoked? can he not have smoked? can we not have smoked? can you not have smoked? can they not have smoked?
V-ing perfect
can I not have been smoking? can you not have been smoking? can he not have been smoking? can we not have been smoking? can you not have been smoking? can they not have been smoking?