English verb conjugation
COULD SKI

Regular verb: ski - skied - skied

Affirmation

Simple form	V-ing form
I could ski you could ski he could ski we could ski you could ski they could ski	I could be skiing you could be skiing he could be skiing we could be skiing you could be skiing they could be skiing
Perfect	V-ing perfect
I could have skied you could have skied he could have skied we could have skied you could have skied they could have skied	I could have been skiing you could have been skiing he could have been skiing we could have been skiing you could have been skiing they could have been skiing

Negation

Simple form	V-ing form
I could not ski you could not ski he could not ski we could not ski you could not ski they could not ski	I could not be skiing you could not be skiing he could not be skiing we could not be skiing you could not be skiing they could not be skiing
Perfect	V-ing perfect
I could not have skied you could not have skied he could not have skied we could not have skied you could not have skied they could not have skied	I could not have been skiing you could not have been skiing he could not have been skiing we could not have been skiing you could not have been skiing they could not have been skiing

Interrogative form

Simple form	V-ing form
could I ski? could you ski? could he ski? could we ski? could you ski? could they ski?	could I be skiing? could you be skiing? could he be skiing? could we be skiing? could you be skiing? could they be skiing?
Perfect	V-ing perfect
could I have skied? could you have skied? could he have skied? could we have skied? could you have skied? could they have skied?	could I have been skiing? could you have been skiing? could he have been skiing? could we have been skiing? could you have been skiing? could they have been skiing?

Interro-negative form

Simple form	V-ing form
could I not ski? could you not ski? could he not ski? could we not ski? could you not ski? could they not ski?	could I not be skiing? could you not be skiing? could he not be skiing? could we not be skiing? could you not be skiing? could they not be skiing?
Perfect	V-ing perfect
could I not have skied? could you not have skied? could he not have skied? could we not have skied? could you not have skied? could they not have skied?	could I not have been skiing? could you not have been skiing? could he not have been skiing? could we not have been skiing? could you not have been skiing? could they not have been skiing?