I can board you can board he can board we can board you can board they can board
V-ing form
I can be boarding you can be boarding he can be boarding we can be boarding you can be boarding they can be boarding
Perfect
I can have boarded you can have boarded he can have boarded we can have boarded you can have boarded they can have boarded
V-ing perfect
I can have been boarding you can have been boarding he can have been boarding we can have been boarding you can have been boarding they can have been boarding
Negation
Simple form
I cannot board you cannot board he cannot board we cannot board you cannot board they cannot board
V-ing form
I cannot be boarding you cannot be boarding he cannot be boarding we cannot be boarding you cannot be boarding they cannot be boarding
Perfect
I cannot have boarded you cannot have boarded he cannot have boarded we cannot have boarded you cannot have boarded they cannot have boarded
V-ing perfect
I cannot have been boarding you cannot have been boarding he cannot have been boarding we cannot have been boarding you cannot have been boarding they cannot have been boarding
Interrogative form
Simple form
can I board? can you board? can he board? can we board? can you board? can they board?
V-ing form
can I be boarding? can you be boarding? can he be boarding? can we be boarding? can you be boarding? can they be boarding?
Perfect
can I have boarded? can you have boarded? can he have boarded? can we have boarded? can you have boarded? can they have boarded?
V-ing perfect
can I have been boarding? can you have been boarding? can he have been boarding? can we have been boarding? can you have been boarding? can they have been boarding?
Interro-negative form
Simple form
can I not board? can you not board? can he not board? can we not board? can you not board? can they not board?
V-ing form
can I not be boarding? can you not be boarding? can he not be boarding? can we not be boarding? can you not be boarding? can they not be boarding?
Perfect
can I not have boarded? can you not have boarded? can he not have boarded? can we not have boarded? can you not have boarded? can they not have boarded?
V-ing perfect
can I not have been boarding? can you not have been boarding? can he not have been boarding? can we not have been boarding? can you not have been boarding? can they not have been boarding?