English verb conjugation
COULD SKI

Regular verb: ski - skied - skied

Affirmation

Simple form	V-ing form
I could ski you could ski she could ski we could ski you could ski they could ski	I could be skiing you could be skiing she 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 she 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 she 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 she 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 she 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 she 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 she 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 she ski? could we ski? could you ski? could they ski?	could I be skiing? could you be skiing? could she 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 she 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 she 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 she 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 she 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 she 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 she have been skiing? couldn't we have been skiing? couldn't you have been skiing? couldn't they have been skiing?