5.D. 主旨大意题。本文主要就火山灰对人的健康的危害问题世卫组织和其他专家给出不同观点。A太笼统;B不能体现不同的观点;C与文章内容无关;D符合题意。
6. A. 细节理解题。第三段最后一句可知A是正确的;由第三段中During a volcanic eruption……in healthy people.可知B错误;由第三段中Other experts, however, weren't convinced…… cigarette smoke or pollution可排除C D。
7. D. 词义猜测题。由上文中volcanic ash is not all that harmful和下文中only those in the near vicinity of the Icelandic volcano would likely be at risk可知D正确, 夸大的，言过其实的。
8.C. 由第三段 But once it falls from a greater distance….. effects are often minimal和第四段中 only those in the near vicinity of the Icelandic volcano would likely be at risk以及第五段中 the further the particles travel, the more diluted and less dangerous they will be可知C正确。ABD观点表达绝对。
9-12 CBAC
