【正确答案】 A

【答案解析】[听力原文] For years scientists have been worried about the effects of air pollution on the earth's natural conditions. Some believe the air inside many houses may be more dangerous than the air outside. It may be one hundred times worse. Indoor air pollution can cause a person to feel tired, to suffer eye-pain, headache and other problems. Some pollutants can cause breathing disorders, diseases of blood and even cancer. Most scientists agree that every modern house has some kind of indoor pollution. People began to notice the problem in the early 1970s. When builders began making houses and offices, they did not waste energy. To do this they built buildings that limited the flow of air between inside and outside. They also began using man-made building materials. These materials are now known to let out harmful gases. As the problem became more serious, scientists began searching for a way to deal with it. They discovered a natural pollution control system for buildings—green plants. Scientists do not really know how plants control air pollution. They believe that a plant's leaves absorb or take in the pollutants. In exchange the plant lets out oxygen through its leaves and through its tiny organizations on its roots. Scientists suggest that all buildings should have one large plant or several small plants inside for every nine square meters of space. Studies of different plants show that each absorbs different chemicals. So the most effective way to clean the air is to use different kinds of plants. According to the speaker, what problem may indoor air pollution bring to people? 由选项可知，本题询问They可能存在哪种身体不适，They应该指人。短文提到，室内空气污染可能使人感觉疲倦、眼痛、头疼等。A中的exhausted对应文中的tired，故答案为A。 C利用类似语音heartache进行干扰，文中提到的是headache，故C不正确。并列处常设考点。

【正确答案】 D

【答案解析】[听力原文] What causes the indoor air pollution according to the speaker? 短文提到，建筑者们为了不浪费能源，他们建造能限制室内与室外之间的空气流动的建筑物，他们还开始使用人造建筑材料。据目前所知，这些材料会释放出有害气体。正是这两个方面导致了室内空气污染，因此本题选D。 内容更综合、全面的选项往往是正确答案。B、C只是导致室内空气污染的其中某个方面，但都不够全面，故不选。

【正确答案】 C

【答案解析】[听力原文] What is the most effective way to clean the air? 短文末句明确提到，使空气清新的最有效方法就是使用各种植物，因此C正确。 体现了“出现形容词和副词最高级的地方常考”及“短文结尾处常出题”这两个命题规律。听到the most时就应格外留意该句的内容。此外，与文章主旨相符的选项往往是正确答案，本文的后半部分主要都是围绕着plants讲述，故也可据此选C。 A、B描述的是植物的作用，但与题目不相符，属于答非所问。