could nitride
Regular verb: nitride - nitrided- nitrided

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could nitride
you could nitride
he could nitride
we could nitride
you could nitride
they could nitride 	I could be nitriding
you could be nitriding
he could be nitriding
we could be nitriding
you could be nitriding
they could be nitriding	I could have nitrided
you could have nitrided
he could have nitrided
we could have nitrided
you could have nitrided
they could have nitrided	I could have been nitriding
you could have been nitriding
he could have been nitriding
we could have been nitriding
you could have been nitriding
they could have been nitriding	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't nitride
you couldn't nitride
he couldn't nitride
we couldn't nitride
you couldn't nitride
they couldn't nitride 	I couldn't be nitriding
you couldn't be nitriding
he couldn't be nitriding
we couldn't be nitriding
you couldn't be nitriding
they couldn't be nitriding	I couldn't have nitrided
you couldn't have nitrided
he couldn't have nitrided
we couldn't have nitrided
you couldn't have nitrided
they couldn't have nitrided	I couldn't have been nitriding
you couldn't have been nitriding
he couldn't have been nitriding
we couldn't have been nitriding
you couldn't have been nitriding
they couldn't have been nitriding	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I nitride?
could you nitride?
could he nitride?
could we nitride?
could you nitride?
could they nitride? 	could I be nitriding?
could you be nitriding?
could he be nitriding?
could we be nitriding?
could you be nitriding?
could they be nitriding? 	could I have nitrided?
could you have nitrided?
could he have nitrided?
could we have nitrided?
could you have nitrided?
could they have nitrided? 	could I have been nitriding?
could you have been nitriding?
could he have been nitriding?
could we have been nitriding?
could you have been nitriding?
could they have been nitriding? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I nitride?
couldn't you nitride?
couldn't he nitride?
couldn't we nitride?
couldn't you nitride?
couldn't they nitride? 	couldn't I be nitriding?
couldn't you be nitriding?
couldn't he be nitriding?
couldn't we be nitriding?
couldn't you be nitriding?
couldn't they be nitriding? 	couldn't I have nitrided?
couldn't you have nitrided?
couldn't he have nitrided?
couldn't we have nitrided?
couldn't you have nitrided?
couldn't they have nitrided? 	couldn't I have been nitriding?
couldn't you have been nitriding?
couldn't he have been nitriding?
couldn't we have been nitriding?
couldn't you have been nitriding?
couldn't they have been nitriding?