Even if scientists did discover another reasonable explanation for the warming recorded so far, that would give birth to a difficult question. As Robert Henson puts it: “If some newly discovered factor is to blame for the climate change, then why aren't carbon dioxide and the other greenhouse gases producing the warming that basic physics tells us they should be？”

　　The only way to prove with 100% certainty that humans are responsible for global warming would be to run an experiment with two identical Earths—one with human influence and one without. That obviously isn't possible, and so most scientists are careful not to state human influence as an absolute certainty.

　　文章大意：全球变暖是不是人类活动的原因？本文进行了探讨。

　　67．In most scientists' opinion, the global warming is mainly caused by________.

　　A. solar activity

　　B. volcanic activity

　　C. natural factors

　　D. human factors

　　答案：D　细节理解题。由第一段可知，全球变暖是由人类活动这一因素引起的。

　　68．The text is developed by________.

　　A. giving typical examples

　　B. following the order of space

　　C. analyzing a theory and arguing it

　　D. comparing and finding differences

　　答案：C　推理判断题。由全文可知，本文先提出了一个理论，然后进行了反驳。

【高三英语备考总复习人教版选修六：Units 3～5质量过关检测】相关文章：

★ 2017届高考英语二轮复习课时训练：19（含解析）

★ 山西省永济市涑北中学高三英语总复习：美文欣赏（2）（Unconditional Love）

★ 贵州省贵阳市2014高考英语（新人教版）一轮阅读训练（25）附答案

★ 最新2016高考英语二轮复习的建议

★ 【北师大版】2014届高考英语一轮复习指导课时作业：Unit 1 A卷 Word版含解析

★ 2014高考英语（新人教版）一轮基础训练（14）A、B卷（附答案或解析）

★ 考生高考第一轮英语复习要做好6件事

★ 15-16高考英语二轮复习如何突破英语易错题

★ 2014高考英语（新人教版）一轮基础训练（20）A、B卷（附答案或解析）

★ 2017届高考英语二轮复习课时训练：21（含解析）