could fertilize
Regular verb: fertilize - fertilized- fertilized

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could fertilize
you could fertilize
she could fertilize
we could fertilize
you could fertilize
they could fertilize 	I could be fertilizing
you could be fertilizing
she could be fertilizing
we could be fertilizing
you could be fertilizing
they could be fertilizing	I could have fertilized
you could have fertilized
she 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
she 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 could not fertilize
you could not fertilize
she could not fertilize
we could not fertilize
you could not fertilize
they could not fertilize 	I could not be fertilizing
you could not be fertilizing
she could not be fertilizing
we could not be fertilizing
you could not be fertilizing
they could not be fertilizing	I could not have fertilized
you could not have fertilized
she could not have fertilized
we could not have fertilized
you could not have fertilized
they could not have fertilized	I could not have been fertilizing
you could not have been fertilizing
she could not have been fertilizing
we could not have been fertilizing
you could not have been fertilizing
they could not have been fertilizing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I fertilize?
could you fertilize?
could she fertilize?
could we fertilize?
could you fertilize?
could they fertilize? 	could I be fertilizing?
could you be fertilizing?
could she be fertilizing?
could we be fertilizing?
could you be fertilizing?
could they be fertilizing? 	could I have fertilized?
could you have fertilized?
could she 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 she 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 	
could I not fertilize?
could you not fertilize?
could she not fertilize?
could we not fertilize?
could you not fertilize?
could they not fertilize? 	could I not be fertilizing?
could you not be fertilizing?
could she not be fertilizing?
could we not be fertilizing?
could you not be fertilizing?
could they not be fertilizing? 	could I not have fertilized?
could you not have fertilized?
could she not have fertilized?
could we not have fertilized?
could you not have fertilized?
could they not have fertilized? 	could I not have been fertilizing?
could you not have been fertilizing?
could she not have been fertilizing?
could we not have been fertilizing?
could you not have been fertilizing?
could they not have been fertilizing?