I can gravel you can gravel he can gravel we can gravel you can gravel they can gravel
V-ing form
I can be gravelling you can be gravelling he can be gravelling we can be gravelling you can be gravelling they can be gravelling
Perfect
I can have gravelled you can have gravelled he can have gravelled we can have gravelled you can have gravelled they can have gravelled
V-ing perfect
I can have been gravelling you can have been gravelling he can have been gravelling we can have been gravelling you can have been gravelling they can have been gravelling
Negation
Simple form
I can't gravel you can't gravel he can't gravel we can't gravel you can't gravel they can't gravel
V-ing form
I can't be gravelling you can't be gravelling he can't be gravelling we can't be gravelling you can't be gravelling they can't be gravelling
Perfect
I can't have gravelled you can't have gravelled he can't have gravelled we can't have gravelled you can't have gravelled they can't have gravelled
V-ing perfect
I can't have been gravelling you can't have been gravelling he can't have been gravelling we can't have been gravelling you can't have been gravelling they can't have been gravelling
Interrogative form
Simple form
can I gravel? can you gravel? can he gravel? can we gravel? can you gravel? can they gravel?
V-ing form
can I be gravelling? can you be gravelling? can he be gravelling? can we be gravelling? can you be gravelling? can they be gravelling?
Perfect
can I have gravelled? can you have gravelled? can he have gravelled? can we have gravelled? can you have gravelled? can they have gravelled?
V-ing perfect
can I have been gravelling? can you have been gravelling? can he have been gravelling? can we have been gravelling? can you have been gravelling? can they have been gravelling?
Interro-negative form
Simple form
can't I gravel? can't you gravel? can't he gravel? can't we gravel? can't you gravel? can't they gravel?
V-ing form
can't I be gravelling? can't you be gravelling? can't he be gravelling? can't we be gravelling? can't you be gravelling? can't they be gravelling?
Perfect
can't I have gravelled? can't you have gravelled? can't he have gravelled? can't we have gravelled? can't you have gravelled? can't they have gravelled?
V-ing perfect
can't I have been gravelling? can't you have been gravelling? can't he have been gravelling? can't we have been gravelling? can't you have been gravelling? can't they have been gravelling?