I can stretch you can stretch he can stretch we can stretch you can stretch they can stretch
V-ing form
I can be stretching you can be stretching he can be stretching we can be stretching you can be stretching they can be stretching
Perfect
I can have stretched you can have stretched he can have stretched we can have stretched you can have stretched they can have stretched
V-ing perfect
I can have been stretching you can have been stretching he can have been stretching we can have been stretching you can have been stretching they can have been stretching
Negation
Simple form
I cannot stretch you cannot stretch he cannot stretch we cannot stretch you cannot stretch they cannot stretch
V-ing form
I cannot be stretching you cannot be stretching he cannot be stretching we cannot be stretching you cannot be stretching they cannot be stretching
Perfect
I cannot have stretched you cannot have stretched he cannot have stretched we cannot have stretched you cannot have stretched they cannot have stretched
V-ing perfect
I cannot have been stretching you cannot have been stretching he cannot have been stretching we cannot have been stretching you cannot have been stretching they cannot have been stretching
Interrogative form
Simple form
can I stretch? can you stretch? can he stretch? can we stretch? can you stretch? can they stretch?
V-ing form
can I be stretching? can you be stretching? can he be stretching? can we be stretching? can you be stretching? can they be stretching?
Perfect
can I have stretched? can you have stretched? can he have stretched? can we have stretched? can you have stretched? can they have stretched?
V-ing perfect
can I have been stretching? can you have been stretching? can he have been stretching? can we have been stretching? can you have been stretching? can they have been stretching?
Interro-negative form
Simple form
can I not stretch? can you not stretch? can he not stretch? can we not stretch? can you not stretch? can they not stretch?
V-ing form
can I not be stretching? can you not be stretching? can he not be stretching? can we not be stretching? can you not be stretching? can they not be stretching?
Perfect
can I not have stretched? can you not have stretched? can he not have stretched? can we not have stretched? can you not have stretched? can they not have stretched?
V-ing perfect
can I not have been stretching? can you not have been stretching? can he not have been stretching? can we not have been stretching? can you not have been stretching? can they not have been stretching?