could fertilize
Regular verb: fertilize - fertilized- fertilized

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could fertilize
you could fertilize
he could fertilize
we could fertilize
you could fertilize
they could fertilize 	I could be fertilizing
you could be fertilizing
he could be fertilizing
we could be fertilizing
you could be fertilizing
they could be fertilizing	I could have fertilized
you could have fertilized
he could have fertilized
we could have fertilized
you could have fertilized
they could have fertilized	I could have been fertilizing
you could have been fertilizing
he could have been fertilizing
we could have been fertilizing
you could have been fertilizing
they could have been fertilizing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't fertilize
you couldn't fertilize
he couldn't fertilize
we couldn't fertilize
you couldn't fertilize
they couldn't fertilize 	I couldn't be fertilizing
you couldn't be fertilizing
he couldn't be fertilizing
we couldn't be fertilizing
you couldn't be fertilizing
they couldn't be fertilizing	I couldn't have fertilized
you couldn't have fertilized
he couldn't have fertilized
we couldn't have fertilized
you couldn't have fertilized
they couldn't have fertilized	I couldn't have been fertilizing
you couldn't have been fertilizing
he couldn't have been fertilizing
we couldn't have been fertilizing
you couldn't have been fertilizing
they couldn't have been fertilizing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I fertilize?
could you fertilize?
could he fertilize?
could we fertilize?
could you fertilize?
could they fertilize? 	could I be fertilizing?
could you be fertilizing?
could he be fertilizing?
could we be fertilizing?
could you be fertilizing?
could they be fertilizing? 	could I have fertilized?
could you have fertilized?
could he have fertilized?
could we have fertilized?
could you have fertilized?
could they have fertilized? 	could I have been fertilizing?
could you have been fertilizing?
could he have been fertilizing?
could we have been fertilizing?
could you have been fertilizing?
could they have been fertilizing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I fertilize?
couldn't you fertilize?
couldn't he fertilize?
couldn't we fertilize?
couldn't you fertilize?
couldn't they fertilize? 	couldn't I be fertilizing?
couldn't you be fertilizing?
couldn't he be fertilizing?
couldn't we be fertilizing?
couldn't you be fertilizing?
couldn't they be fertilizing? 	couldn't I have fertilized?
couldn't you have fertilized?
couldn't he have fertilized?
couldn't we have fertilized?
couldn't you have fertilized?
couldn't they have fertilized? 	couldn't I have been fertilizing?
couldn't you have been fertilizing?
couldn't he have been fertilizing?
couldn't we have been fertilizing?
couldn't you have been fertilizing?
couldn't they have been fertilizing?