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