In an introductory note to this chapter, the Kitzur Shulchan Aruch writes that most Jews are already familiar with the prohibited labors of Shabbos and that he is only addressing common situations with which people may not be familiar. Clearly, the laws of Shabbos constitute an area requiring much greater study than this email alone will allow.
80:33 One may not cover a barrel of water with a cloth that isn't designated for that purpose because if it falls in, one may very likely come to wring it out. If a cloth is designated for this purpose, it is allowed. Since this is its specific purpose, we aren't concerned that one will wring it out.
80:34 If water spills on a table or elsewhere, we may not wipe it up with a garment that one cares about. This is because if there's a lot of water, he may very likely come to wring it out. Similarly, one should not use a cloth to dry cups or other dishes that have narrow openings. The reason for this is because squeezing the cloth through these openings will cause water to be wrung out.