English verb conjugation
COULD CHALLENGE

Regular verb: challenge - challenged - challenged

Affirmation

Simple form	V-ing form
I could challenge you could challenge he could challenge we could challenge you could challenge they could challenge	I could be challenging you could be challenging he could be challenging we could be challenging you could be challenging they could be challenging
Perfect	V-ing perfect
I could have challenged you could have challenged he could have challenged we could have challenged you could have challenged they could have challenged	I could have been challenging you could have been challenging he could have been challenging we could have been challenging you could have been challenging they could have been challenging

Negation

Simple form	V-ing form
I couldn't challenge you couldn't challenge he couldn't challenge we couldn't challenge you couldn't challenge they couldn't challenge	I couldn't be challenging you couldn't be challenging he couldn't be challenging we couldn't be challenging you couldn't be challenging they couldn't be challenging
Perfect	V-ing perfect
I couldn't have challenged you couldn't have challenged he couldn't have challenged we couldn't have challenged you couldn't have challenged they couldn't have challenged	I couldn't have been challenging you couldn't have been challenging he couldn't have been challenging we couldn't have been challenging you couldn't have been challenging they couldn't have been challenging

Interrogative form

Simple form	V-ing form
could I challenge? could you challenge? could he challenge? could we challenge? could you challenge? could they challenge?	could I be challenging? could you be challenging? could he be challenging? could we be challenging? could you be challenging? could they be challenging?
Perfect	V-ing perfect
could I have challenged? could you have challenged? could he have challenged? could we have challenged? could you have challenged? could they have challenged?	could I have been challenging? could you have been challenging? could he have been challenging? could we have been challenging? could you have been challenging? could they have been challenging?

Interro-negative form

Simple form	V-ing form
couldn't I challenge? couldn't you challenge? couldn't he challenge? couldn't we challenge? couldn't you challenge? couldn't they challenge?	couldn't I be challenging? couldn't you be challenging? couldn't he be challenging? couldn't we be challenging? couldn't you be challenging? couldn't they be challenging?
Perfect	V-ing perfect
couldn't I have challenged? couldn't you have challenged? couldn't he have challenged? couldn't we have challenged? couldn't you have challenged? couldn't they have challenged?	couldn't I have been challenging? couldn't you have been challenging? couldn't he have been challenging? couldn't we have been challenging? couldn't you have been challenging? couldn't they have been challenging?