English verb conjugation
COULD HEIGHTEN

Regular verb: heighten - heightened - heightened

Affirmation

Simple form	V-ing form
I could heighten you could heighten he could heighten we could heighten you could heighten they could heighten	I could be heightening you could be heightening he could be heightening we could be heightening you could be heightening they could be heightening
Perfect	V-ing perfect
I could have heightened you could have heightened he could have heightened we could have heightened you could have heightened they could have heightened	I could have been heightening you could have been heightening he could have been heightening we could have been heightening you could have been heightening they could have been heightening

Negation

Simple form	V-ing form
I could not heighten you could not heighten he could not heighten we could not heighten you could not heighten they could not heighten	I could not be heightening you could not be heightening he could not be heightening we could not be heightening you could not be heightening they could not be heightening
Perfect	V-ing perfect
I could not have heightened you could not have heightened he could not have heightened we could not have heightened you could not have heightened they could not have heightened	I could not have been heightening you could not have been heightening he could not have been heightening we could not have been heightening you could not have been heightening they could not have been heightening

Interrogative form

Simple form	V-ing form
could I heighten? could you heighten? could he heighten? could we heighten? could you heighten? could they heighten?	could I be heightening? could you be heightening? could he be heightening? could we be heightening? could you be heightening? could they be heightening?
Perfect	V-ing perfect
could I have heightened? could you have heightened? could he have heightened? could we have heightened? could you have heightened? could they have heightened?	could I have been heightening? could you have been heightening? could he have been heightening? could we have been heightening? could you have been heightening? could they have been heightening?

Interro-negative form

Simple form	V-ing form
could I not heighten? could you not heighten? could he not heighten? could we not heighten? could you not heighten? could they not heighten?	could I not be heightening? could you not be heightening? could he not be heightening? could we not be heightening? could you not be heightening? could they not be heightening?
Perfect	V-ing perfect
could I not have heightened? could you not have heightened? could he not have heightened? could we not have heightened? could you not have heightened? could they not have heightened?	could I not have been heightening? could you not have been heightening? could he not have been heightening? could we not have been heightening? could you not have been heightening? could they not have been heightening?