English verb conjugation
COULD STRAIGHTEN

Regular verb: straighten - straightened - straightened

Affirmation

Simple form	V-ing form
I could straighten you could straighten he could straighten we could straighten you could straighten they could straighten	I could be straightening you could be straightening he could be straightening we could be straightening you could be straightening they could be straightening
Perfect	V-ing perfect
I could have straightened you could have straightened he could have straightened we could have straightened you could have straightened they could have straightened	I could have been straightening you could have been straightening he could have been straightening we could have been straightening you could have been straightening they could have been straightening

Negation

Simple form	V-ing form
I couldn't straighten you couldn't straighten he couldn't straighten we couldn't straighten you couldn't straighten they couldn't straighten	I couldn't be straightening you couldn't be straightening he couldn't be straightening we couldn't be straightening you couldn't be straightening they couldn't be straightening
Perfect	V-ing perfect
I couldn't have straightened you couldn't have straightened he couldn't have straightened we couldn't have straightened you couldn't have straightened they couldn't have straightened	I couldn't have been straightening you couldn't have been straightening he couldn't have been straightening we couldn't have been straightening you couldn't have been straightening they couldn't have been straightening

Interrogative form

Simple form	V-ing form
could I straighten? could you straighten? could he straighten? could we straighten? could you straighten? could they straighten?	could I be straightening? could you be straightening? could he be straightening? could we be straightening? could you be straightening? could they be straightening?
Perfect	V-ing perfect
could I have straightened? could you have straightened? could he have straightened? could we have straightened? could you have straightened? could they have straightened?	could I have been straightening? could you have been straightening? could he have been straightening? could we have been straightening? could you have been straightening? could they have been straightening?

Interro-negative form

Simple form	V-ing form
couldn't I straighten? couldn't you straighten? couldn't he straighten? couldn't we straighten? couldn't you straighten? couldn't they straighten?	couldn't I be straightening? couldn't you be straightening? couldn't he be straightening? couldn't we be straightening? couldn't you be straightening? couldn't they be straightening?
Perfect	V-ing perfect
couldn't I have straightened? couldn't you have straightened? couldn't he have straightened? couldn't we have straightened? couldn't you have straightened? couldn't they have straightened?	couldn't I have been straightening? couldn't you have been straightening? couldn't he have been straightening? couldn't we have been straightening? couldn't you have been straightening? couldn't they have been straightening?