I can fast you can fast he can fast we can fast you can fast they can fast
V-ing form
I can be fasting you can be fasting he can be fasting we can be fasting you can be fasting they can be fasting
Perfect
I can have fasted you can have fasted he can have fasted we can have fasted you can have fasted they can have fasted
V-ing perfect
I can have been fasting you can have been fasting he can have been fasting we can have been fasting you can have been fasting they can have been fasting
Negation
Simple form
I cannot fast you cannot fast he cannot fast we cannot fast you cannot fast they cannot fast
V-ing form
I cannot be fasting you cannot be fasting he cannot be fasting we cannot be fasting you cannot be fasting they cannot be fasting
Perfect
I cannot have fasted you cannot have fasted he cannot have fasted we cannot have fasted you cannot have fasted they cannot have fasted
V-ing perfect
I cannot have been fasting you cannot have been fasting he cannot have been fasting we cannot have been fasting you cannot have been fasting they cannot have been fasting
Interrogative form
Simple form
can I fast? can you fast? can he fast? can we fast? can you fast? can they fast?
V-ing form
can I be fasting? can you be fasting? can he be fasting? can we be fasting? can you be fasting? can they be fasting?
Perfect
can I have fasted? can you have fasted? can he have fasted? can we have fasted? can you have fasted? can they have fasted?
V-ing perfect
can I have been fasting? can you have been fasting? can he have been fasting? can we have been fasting? can you have been fasting? can they have been fasting?
Interro-negative form
Simple form
can I not fast? can you not fast? can he not fast? can we not fast? can you not fast? can they not fast?
V-ing form
can I not be fasting? can you not be fasting? can he not be fasting? can we not be fasting? can you not be fasting? can they not be fasting?
Perfect
can I not have fasted? can you not have fasted? can he not have fasted? can we not have fasted? can you not have fasted? can they not have fasted?
V-ing perfect
can I not have been fasting? can you not have been fasting? can he not have been fasting? can we not have been fasting? can you not have been fasting? can they not have been fasting?