I can gain you can gain he can gain we can gain you can gain they can gain
V-ing form
I can be gaining you can be gaining he can be gaining we can be gaining you can be gaining they can be gaining
Perfect
I can have gained you can have gained he can have gained we can have gained you can have gained they can have gained
V-ing perfect
I can have been gaining you can have been gaining he can have been gaining we can have been gaining you can have been gaining they can have been gaining
Negation
Simple form
I cannot gain you cannot gain he cannot gain we cannot gain you cannot gain they cannot gain
V-ing form
I cannot be gaining you cannot be gaining he cannot be gaining we cannot be gaining you cannot be gaining they cannot be gaining
Perfect
I cannot have gained you cannot have gained he cannot have gained we cannot have gained you cannot have gained they cannot have gained
V-ing perfect
I cannot have been gaining you cannot have been gaining he cannot have been gaining we cannot have been gaining you cannot have been gaining they cannot have been gaining
Interrogative form
Simple form
can I gain? can you gain? can he gain? can we gain? can you gain? can they gain?
V-ing form
can I be gaining? can you be gaining? can he be gaining? can we be gaining? can you be gaining? can they be gaining?
Perfect
can I have gained? can you have gained? can he have gained? can we have gained? can you have gained? can they have gained?
V-ing perfect
can I have been gaining? can you have been gaining? can he have been gaining? can we have been gaining? can you have been gaining? can they have been gaining?
Interro-negative form
Simple form
can I not gain? can you not gain? can he not gain? can we not gain? can you not gain? can they not gain?
V-ing form
can I not be gaining? can you not be gaining? can he not be gaining? can we not be gaining? can you not be gaining? can they not be gaining?
Perfect
can I not have gained? can you not have gained? can he not have gained? can we not have gained? can you not have gained? can they not have gained?
V-ing perfect
can I not have been gaining? can you not have been gaining? can he not have been gaining? can we not have been gaining? can you not have been gaining? can they not have been gaining?