I can grind you can grind he can grind we can grind you can grind they can grind
V-ing form
I can be grinding you can be grinding he can be grinding we can be grinding you can be grinding they can be grinding
Perfect
I can have ground you can have ground he can have ground we can have ground you can have ground they can have ground
V-ing perfect
I can have been grinding you can have been grinding he can have been grinding we can have been grinding you can have been grinding they can have been grinding
Negation
Simple form
I can't grind you can't grind he can't grind we can't grind you can't grind they can't grind
V-ing form
I can't be grinding you can't be grinding he can't be grinding we can't be grinding you can't be grinding they can't be grinding
Perfect
I can't have ground you can't have ground he can't have ground we can't have ground you can't have ground they can't have ground
V-ing perfect
I can't have been grinding you can't have been grinding he can't have been grinding we can't have been grinding you can't have been grinding they can't have been grinding
Interrogative form
Simple form
can I grind? can you grind? can he grind? can we grind? can you grind? can they grind?
V-ing form
can I be grinding? can you be grinding? can he be grinding? can we be grinding? can you be grinding? can they be grinding?
Perfect
can I have ground? can you have ground? can he have ground? can we have ground? can you have ground? can they have ground?
V-ing perfect
can I have been grinding? can you have been grinding? can he have been grinding? can we have been grinding? can you have been grinding? can they have been grinding?
Interro-negative form
Simple form
can't I grind? can't you grind? can't he grind? can't we grind? can't you grind? can't they grind?
V-ing form
can't I be grinding? can't you be grinding? can't he be grinding? can't we be grinding? can't you be grinding? can't they be grinding?
Perfect
can't I have ground? can't you have ground? can't he have ground? can't we have ground? can't you have ground? can't they have ground?
V-ing perfect
can't I have been grinding? can't you have been grinding? can't he have been grinding? can't we have been grinding? can't you have been grinding? can't they have been grinding?