I can excel you can excel he can excel we can excel you can excel they can excel
V-ing form
I can be excelling you can be excelling he can be excelling we can be excelling you can be excelling they can be excelling
Perfect
I can have excelled you can have excelled he can have excelled we can have excelled you can have excelled they can have excelled
V-ing perfect
I can have been excelling you can have been excelling he can have been excelling we can have been excelling you can have been excelling they can have been excelling
Negation
Simple form
I can't excel you can't excel he can't excel we can't excel you can't excel they can't excel
V-ing form
I can't be excelling you can't be excelling he can't be excelling we can't be excelling you can't be excelling they can't be excelling
Perfect
I can't have excelled you can't have excelled he can't have excelled we can't have excelled you can't have excelled they can't have excelled
V-ing perfect
I can't have been excelling you can't have been excelling he can't have been excelling we can't have been excelling you can't have been excelling they can't have been excelling
Interrogative form
Simple form
can I excel? can you excel? can he excel? can we excel? can you excel? can they excel?
V-ing form
can I be excelling? can you be excelling? can he be excelling? can we be excelling? can you be excelling? can they be excelling?
Perfect
can I have excelled? can you have excelled? can he have excelled? can we have excelled? can you have excelled? can they have excelled?
V-ing perfect
can I have been excelling? can you have been excelling? can he have been excelling? can we have been excelling? can you have been excelling? can they have been excelling?
Interro-negative form
Simple form
can't I excel? can't you excel? can't he excel? can't we excel? can't you excel? can't they excel?
V-ing form
can't I be excelling? can't you be excelling? can't he be excelling? can't we be excelling? can't you be excelling? can't they be excelling?
Perfect
can't I have excelled? can't you have excelled? can't he have excelled? can't we have excelled? can't you have excelled? can't they have excelled?
V-ing perfect
can't I have been excelling? can't you have been excelling? can't he have been excelling? can't we have been excelling? can't you have been excelling? can't they have been excelling?