English verb conjugation
COULD FERTILIZE

Regular verb: fertilize - fertilized - fertilized

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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
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
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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?