【正确答案】 C

【答案解析】[听力原文]11-13 Today we'll go on to the second part of the "Skin Protection Series". Last time I said something about the importance of keeping our skin clean, and today I' 11 give a talk on sunburn, followed by a talk on skin diseases next week. Sunburn is a very common skin problem, especially in summer. The rays of sunlight are of several different kinds. Some of them, called actinic rays, cause the chemical changes that make photography possible and also cause your skin to become red and burned if you are exposed to them too long. Serious sunburns often occur at the beaches and on snow-covered mountains, where the glare of the sun is reflected back from the sand and water or snow and ice. Other rays of sunlight, called ultraviolet rays, supply needed Vitamin D to your body. Therefore it is helpful to your health to be in the sunlight but dangerous or at least unpleasant if you overexpose to the actinic rays which causes the condition known as sunburn. Hazy days also are dangerous, because the sunlight can burn the skin even when it has to come through clouds. The problem is solved by exposing the body to sunlight gradually, for example, 15 minutes the first day, and a few minutes more each day after that, until the skin has a brown appearance that is called a suntan. People with fair skins have to be much more careful than people with darker skins. Children and babies have very tender skin that burns easily. If a person does get a sunburn he or she should stay out of the sun. A soothing dressing, applied to the burned skin, may help to relieve the pain.