English verb conjugation
COULD PRESERVE

Regular verb: preserve - preserved - preserved

Affirmation

Simple form	V-ing form
I could preserve you could preserve he could preserve we could preserve you could preserve they could preserve	I could be preserving you could be preserving he could be preserving we could be preserving you could be preserving they could be preserving
Perfect	V-ing perfect
I could have preserved you could have preserved he could have preserved we could have preserved you could have preserved they could have preserved	I could have been preserving you could have been preserving he could have been preserving we could have been preserving you could have been preserving they could have been preserving

Negation

Simple form	V-ing form
I couldn't preserve you couldn't preserve he couldn't preserve we couldn't preserve you couldn't preserve they couldn't preserve	I couldn't be preserving you couldn't be preserving he couldn't be preserving we couldn't be preserving you couldn't be preserving they couldn't be preserving
Perfect	V-ing perfect
I couldn't have preserved you couldn't have preserved he couldn't have preserved we couldn't have preserved you couldn't have preserved they couldn't have preserved	I couldn't have been preserving you couldn't have been preserving he couldn't have been preserving we couldn't have been preserving you couldn't have been preserving they couldn't have been preserving

Interrogative form

Simple form	V-ing form
could I preserve? could you preserve? could he preserve? could we preserve? could you preserve? could they preserve?	could I be preserving? could you be preserving? could he be preserving? could we be preserving? could you be preserving? could they be preserving?
Perfect	V-ing perfect
could I have preserved? could you have preserved? could he have preserved? could we have preserved? could you have preserved? could they have preserved?	could I have been preserving? could you have been preserving? could he have been preserving? could we have been preserving? could you have been preserving? could they have been preserving?

Interro-negative form

Simple form	V-ing form
couldn't I preserve? couldn't you preserve? couldn't he preserve? couldn't we preserve? couldn't you preserve? couldn't they preserve?	couldn't I be preserving? couldn't you be preserving? couldn't he be preserving? couldn't we be preserving? couldn't you be preserving? couldn't they be preserving?
Perfect	V-ing perfect
couldn't I have preserved? couldn't you have preserved? couldn't he have preserved? couldn't we have preserved? couldn't you have preserved? couldn't they have preserved?	couldn't I have been preserving? couldn't you have been preserving? couldn't he have been preserving? couldn't we have been preserving? couldn't you have been preserving? couldn't they have been preserving?