I can board you can board she can board we can board you can board they can board
V-ing form
I can be boarding you can be boarding she can be boarding we can be boarding you can be boarding they can be boarding
Perfect
I can have boarded you can have boarded she 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 she 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 she cannot board we cannot board you cannot board they cannot board
V-ing form
I cannot be boarding you cannot be boarding she cannot be boarding we cannot be boarding you cannot be boarding they cannot be boarding
Perfect
I cannot have boarded you cannot have boarded she 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 she 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 she board? can we board? can you board? can they board?
V-ing form
can I be boarding? can you be boarding? can she be boarding? can we be boarding? can you be boarding? can they be boarding?
Perfect
can I have boarded? can you have boarded? can she 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 she 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 she 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 she 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 she 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 she not have been boarding? can we not have been boarding? can you not have been boarding? can they not have been boarding?