第12题: [单项选择]Questions 23 to 25 are based on the conversation you have just heard.[A] They are found under the oceans. [C] Their emissions created earth’s atmosphere. [B] They were most active when earth was first formed. [D] Their fumes are mostly water in the state of a gas. 参考答案:D 答案解析:[听力原文] What aspect of volcanoes does the woman mention
第17题: [单项选择]_______ is the center of our planetary system was a difficult concept to grasp in the Middle Age. A. It is the sun and not the earth B. Being the sun and not the earth C. The sun and not the earth D. That the sun and not the earth 参考答案:D 答案解析:根据句子结构我们可以看出，在was前面是一个主语从句，而主语从句必须有引导词，但A，B和C中都没有引导词，因此三个均错。D中that引导主语从句，在句中不作任何成分，只起引导词的作用，因而D是正确答案
第30题: [单项选择]少尿的定义是 A. 每日尿量少于100ml，每小时尿量持续少于17ml B. 每日尿量少于400ml，每小时尿量持续少于17ml C. 每日尿量少于400ml，每小时尿量持续少于l0ml D. 每日尿量少于400ml，每小时尿量持续少于20ml E. 每日尿量少于50ml，每小时尿量少于17ml 参考答案:B 答案解析:[解题思路] 少尿的定义是每日尿量少于400ml，每小时尿量持续少于17ml。
