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 could not foil you could not foil he could not foil we could not foil you could not foil they could not foil	I could not be foiling you could not be foiling he could not be foiling we could not be foiling you could not be foiling they could not be foiling
Perfect	V-ing perfect
I could not have foiled you could not have foiled he could not have foiled we could not have foiled you could not have foiled they could not have foiled	I could not have been foiling you could not have been foiling he could not have been foiling we could not have been foiling you could not have been foiling they could not 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
could I not foil? could you not foil? could he not foil? could we not foil? could you not foil? could they not foil?	could I not be foiling? could you not be foiling? could he not be foiling? could we not be foiling? could you not be foiling? could they not be foiling?
Perfect	V-ing perfect
could I not have foiled? could you not have foiled? could he not have foiled? could we not have foiled? could you not have foiled? could they not have foiled?	could I not have been foiling? could you not have been foiling? could he not have been foiling? could we not have been foiling? could you not have been foiling? could they not have been foiling?