English verb conjugation
CAN SKI

Regular verb: ski - skied - skied

Affirmation

Simple form	V-ing form
I can ski you can ski he can ski we can ski you can ski they can ski	I can be skiing you can be skiing he 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 he 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 he 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 can't ski you can't ski he can't ski we can't ski you can't ski they can't ski	I can't be skiing you can't be skiing he can't be skiing we can't be skiing you can't be skiing they can't be skiing
Perfect	V-ing perfect
I can't have skied you can't have skied he can't have skied we can't have skied you can't have skied they can't have skied	I can't have been skiing you can't have been skiing he can't have been skiing we can't have been skiing you can't have been skiing they can't have been skiing

Interrogative form

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