How do you spell skis?

Answer 1

If you mean long strip on which people glide on snow then your spelling is correct. If you meant something else, such as "hits the ball vertically" or something else, then context in the question would help.

Answer 2

Skiing is spelt the correct way in the question S-K-I-I-N-G.

Answer 3

That is the correct spelling of the word "skies" (plural of sky).