题干

化学与人类生活密切相关。下列说法正确的是(   )

A:苯酚有一定毒性,不能作消毒剂和防腐剂

B:凡含有食品添加剂的食物对人体健康均有害,不可食用

C:油脂皂化生成的高级脂肪酸钠是肥皂的有效成分

D:用食醋去除水壶中的水垢时所发生的是水解反应

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答案(点此获取答案解析)

C

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    Art is considered by many people to be no more than a decorative means of giving pleasure. This is not always the case, however, at times, art may be seen to have a purely functional side as well. Such could be said of the sandpaintings of the Navaho Indians of the American Southwest; these have a medicinal as well as an artistic purpose.

    According to Navaho traditions, one who suffers from either a mental or a physical illness has in some way disturbed or get in touch with the supernatural—perhaps a certain animal, a ghost, or the dead. To break away from this, the ill person or one of his relatives will employ a medical man called a "singer" to perform a curing ceremony which will attract a powerful supernatural being. During the ceremony, which may last from 2 to 9 days, the "singer" will produce a sandpainting on the floor. On the last day of the ceremony, the patient will sit on this sandpainting and the "singer" will rub the sick or injured parts of the patient's body with sand from a specific figure in the sandpainting. In this way the patient absorbs the power of that particular supernatural being and becomes strong. After the ceremony, the sandpainting is destroyed so its power won't harm anyone.

    The art of sandpainting is handed down from old "singers". The materials used are easily found where the Navaho settle: brown, red, yellow, and white sandstone, which is ground(研磨)much as corn is made into flour. The "singer" holds a small amount of this sand in his hand and lets it flow between his fingers onto a clean, flat surface on the floor, with a steady hand and great patience. He is thus able to create designs of stylized people, snakes and other creatures that have power in the Navaho belief system. The traditional Navaho doesn't allow copying sandpaintings, since he believes the supernatural powers that taught him the craft have forbidden this; however, such reproductions can in fact be purchased today in tourist shops in Arizona and New Mexico. These are done by either Navaho Indians or by other people who wish to preserve this craft.