I can water-ski you can water-ski she can water-ski we can water-ski you can water-ski they can water-ski
V-ing form
I can be water-skiing you can be water-skiing she can be water-skiing we can be water-skiing you can be water-skiing they can be water-skiing
Perfect
I can have water-skied you can have water-skied she can have water-skied we can have water-skied you can have water-skied they can have water-skied
V-ing perfect
I can have been water-skiing you can have been water-skiing she can have been water-skiing we can have been water-skiing you can have been water-skiing they can have been water-skiing
Negation
Simple form
I cannot water-ski you cannot water-ski she cannot water-ski we cannot water-ski you cannot water-ski they cannot water-ski
V-ing form
I cannot be water-skiing you cannot be water-skiing she cannot be water-skiing we cannot be water-skiing you cannot be water-skiing they cannot be water-skiing
Perfect
I cannot have water-skied you cannot have water-skied she cannot have water-skied we cannot have water-skied you cannot have water-skied they cannot have water-skied
V-ing perfect
I cannot have been water-skiing you cannot have been water-skiing she cannot have been water-skiing we cannot have been water-skiing you cannot have been water-skiing they cannot have been water-skiing
Interrogative form
Simple form
can I water-ski? can you water-ski? can she water-ski? can we water-ski? can you water-ski? can they water-ski?
V-ing form
can I be water-skiing? can you be water-skiing? can she be water-skiing? can we be water-skiing? can you be water-skiing? can they be water-skiing?
Perfect
can I have water-skied? can you have water-skied? can she have water-skied? can we have water-skied? can you have water-skied? can they have water-skied?
V-ing perfect
can I have been water-skiing? can you have been water-skiing? can she have been water-skiing? can we have been water-skiing? can you have been water-skiing? can they have been water-skiing?
Interro-negative form
Simple form
can I not water-ski? can you not water-ski? can she not water-ski? can we not water-ski? can you not water-ski? can they not water-ski?
V-ing form
can I not be water-skiing? can you not be water-skiing? can she not be water-skiing? can we not be water-skiing? can you not be water-skiing? can they not be water-skiing?
Perfect
can I not have water-skied? can you not have water-skied? can she not have water-skied? can we not have water-skied? can you not have water-skied? can they not have water-skied?
V-ing perfect
can I not have been water-skiing? can you not have been water-skiing? can she not have been water-skiing? can we not have been water-skiing? can you not have been water-skiing? can they not have been water-skiing?