could grind
Irregular verb: grind - ground- ground

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could grind
you could grind
he could grind
we could grind
you could grind
they could grind 	I could be grinding
you could be grinding
he could be grinding
we could be grinding
you could be grinding
they could be grinding	I could have ground
you could have ground
he could have ground
we could have ground
you could have ground
they could have ground	I could have been grinding
you could have been grinding
he could have been grinding
we could have been grinding
you could have been grinding
they could have been grinding	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not grind
you could not grind
he could not grind
we could not grind
you could not grind
they could not grind 	I could not be grinding
you could not be grinding
he could not be grinding
we could not be grinding
you could not be grinding
they could not be grinding	I could not have ground
you could not have ground
he could not have ground
we could not have ground
you could not have ground
they could not have ground	I could not have been grinding
you could not have been grinding
he could not have been grinding
we could not have been grinding
you could not have been grinding
they could not have been grinding	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I grind?
could you grind?
could he grind?
could we grind?
could you grind?
could they grind? 	could I be grinding?
could you be grinding?
could he be grinding?
could we be grinding?
could you be grinding?
could they be grinding? 	could I have ground?
could you have ground?
could he have ground?
could we have ground?
could you have ground?
could they have ground? 	could I have been grinding?
could you have been grinding?
could he have been grinding?
could we have been grinding?
could you have been grinding?
could they have been grinding? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not grind?
could you not grind?
could he not grind?
could we not grind?
could you not grind?
could they not grind? 	could I not be grinding?
could you not be grinding?
could he not be grinding?
could we not be grinding?
could you not be grinding?
could they not be grinding? 	could I not have ground?
could you not have ground?
could he not have ground?
could we not have ground?
could you not have ground?
could they not have ground? 	could I not have been grinding?
could you not have been grinding?
could he not have been grinding?
could we not have been grinding?
could you not have been grinding?
could they not have been grinding?