could foil
Regular verb: foil - foiled- foiled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could foil
you could foil
she could foil
we could foil
you could foil
they could foil 	I could be foiling
you could be foiling
she could be foiling
we could be foiling
you could be foiling
they could be foiling	I could have foiled
you could have foiled
she 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
she 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 	Perfect 	V-ing perfect 	
I could not foil
you could not foil
she 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
she could not be foiling
we could not be foiling
you could not be foiling
they could not be foiling	I could not have foiled
you could not have foiled
she 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
she 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 	Perfect 	V-ing perfect 	
could I foil?
could you foil?
could she foil?
could we foil?
could you foil?
could they foil? 	could I be foiling?
could you be foiling?
could she be foiling?
could we be foiling?
could you be foiling?
could they be foiling? 	could I have foiled?
could you have foiled?
could she 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 she 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 	Perfect 	V-ing perfect 	
could I not foil?
could you not foil?
could she 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 she not be foiling?
could we not be foiling?
could you not be foiling?
could they not be foiling? 	could I not have foiled?
could you not have foiled?
could she 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 she not have been foiling?
could we not have been foiling?
could you not have been foiling?
could they not have been foiling?