English verb conjugation
COULD FOIL

Regular verb: foil - foiled - foiled

Affirmation

Simple form	V-ing form
I could foil you could foil he could foil we could foil you could foil they could foil	I could be foiling you could be foiling he could be foiling we could be foiling you could be foiling they could be foiling
Perfect	V-ing perfect
I could have foiled you could have foiled he could have foiled we could have foiled you could have foiled they could have foiled	I could have been foiling you could have been foiling he could have been foiling we could have been foiling you could have been foiling they could have been foiling

Negation

Simple form	V-ing form
I couldn't foil you couldn't foil he couldn't foil we couldn't foil you couldn't foil they couldn't foil	I couldn't be foiling you couldn't be foiling he couldn't be foiling we couldn't be foiling you couldn't be foiling they couldn't be foiling
Perfect	V-ing perfect
I couldn't have foiled you couldn't have foiled he couldn't have foiled we couldn't have foiled you couldn't have foiled they couldn't have foiled	I couldn't have been foiling you couldn't have been foiling he couldn't have been foiling we couldn't have been foiling you couldn't have been foiling they couldn't have been foiling

Interrogative form

Simple form	V-ing form
could I foil? could you foil? could he foil? could we foil? could you foil? could they foil?	could I be foiling? could you be foiling? could he be foiling? could we be foiling? could you be foiling? could they be foiling?
Perfect	V-ing perfect
could I have foiled? could you have foiled? could he have foiled? could we have foiled? could you have foiled? could they have foiled?	could I have been foiling? could you have been foiling? could he have been foiling? could we have been foiling? could you have been foiling? could they have been foiling?

Interro-negative form

Simple form	V-ing form
couldn't I foil? couldn't you foil? couldn't he foil? couldn't we foil? couldn't you foil? couldn't they foil?	couldn't I be foiling? couldn't you be foiling? couldn't he be foiling? couldn't we be foiling? couldn't you be foiling? couldn't they be foiling?
Perfect	V-ing perfect
couldn't I have foiled? couldn't you have foiled? couldn't he have foiled? couldn't we have foiled? couldn't you have foiled? couldn't they have foiled?	couldn't I have been foiling? couldn't you have been foiling? couldn't he have been foiling? couldn't we have been foiling? couldn't you have been foiling? couldn't they have been foiling?