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 couldn't ski you couldn't ski he couldn't ski we couldn't ski you couldn't ski they couldn't ski	I couldn't be skiing you couldn't be skiing he couldn't be skiing we couldn't be skiing you couldn't be skiing they couldn't be skiing
Perfect	V-ing perfect
I couldn't have skied you couldn't have skied he couldn't have skied we couldn't have skied you couldn't have skied they couldn't have skied	I couldn't have been skiing you couldn't have been skiing he couldn't have been skiing we couldn't have been skiing you couldn't have been skiing they couldn't 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
couldn't I ski? couldn't you ski? couldn't he ski? couldn't we ski? couldn't you ski? couldn't they ski?	couldn't I be skiing? couldn't you be skiing? couldn't he be skiing? couldn't we be skiing? couldn't you be skiing? couldn't they be skiing?
Perfect	V-ing perfect
couldn't I have skied? couldn't you have skied? couldn't he have skied? couldn't we have skied? couldn't you have skied? couldn't they have skied?	couldn't I have been skiing? couldn't you have been skiing? couldn't he have been skiing? couldn't we have been skiing? couldn't you have been skiing? couldn't they have been skiing?