English verb conjugation
CAN SKI

Regular verb: ski - skied - skied

Affirmation

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

Negation

Simple form	V-ing form
I cannot ski you cannot ski she cannot ski we cannot ski you cannot ski they cannot ski	I cannot be skiing you cannot be skiing she cannot be skiing we cannot be skiing you cannot be skiing they cannot be skiing
Perfect	V-ing perfect
I cannot have skied you cannot have skied she cannot have skied we cannot have skied you cannot have skied they cannot have skied	I cannot have been skiing you cannot have been skiing she cannot have been skiing we cannot have been skiing you cannot have been skiing they cannot have been skiing

Interrogative form

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

Interro-negative form

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