can ski
Regular verb: ski - skied- skied

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
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	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 	Perfect 	V-ing perfect 	
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	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 	Perfect 	V-ing perfect 	
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? 	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 	Perfect 	V-ing perfect 	
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? 	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?