70．D 　推理判断题。根据最后一段中的内容可知，研究人员认为有一点很清楚：从少年到成年，每个人都在调整自己对未来生活的满意度，从乐观，到适度到悲观。故D正确。

　　C8 [2017·江苏卷] ----C

　　If a diver surfaces too quickly，he may suffer the bends.Nitrogen(氮)dissolved(溶解)in his blood is suddenly liberated by the reduction of pressure.The consequence，if the bubbles(气泡)accumulate in a joint，is sharp pain and a bent body—thus the name.If the bubbles form in his lungs or his brain，the consequence can be death.

　　Other air－breathing animals also suffer this decompression (减压) sickness if they surface too fast：whales, for example.And so, long ago, did ichthyosaurs.That these ancient sea animals got the bends can be seen from their bones.If bubbles of nitrogen form inside the bone they can cut off its blood supply.This kills the cells in the bone，and consequently weakens it，sometimes to the point of collapse.Fossil(化石) bones that have caved in on themselves are thus a sign that the animal once had the bends.

　　Bruce Rothschild of the University of Kansas knew all this when he began a study of ichthyosaur bones to find out how widespread the problem was in the past.What he particularly wanted to investigate was how ichthyosaurs adapted to the problem of decompression over the 150 million years.To this end, he and his colleagues traveled the world's natural－history museums, looking at hundreds of ichthyosaurs from the Triassic period and from the later Jurassic and Cretaceous periods.

【2017届河北省高考英语阅读理解一轮限时训练（7）】相关文章：

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (21)

★ 贵州省贵阳市2014高考英语（新人教版）一轮阅读训练（39）附答案

★ 四川省2016届高考英语一轮复习课时作业（34） Module 4 Music 外研版选修6

★ 2014届高考英语一轮复习课时作业(八)必修2Module 2《No Drugs》（外研版）

★ 2017届高考英语二轮复习课时训练：17（含解析）

★ 浙江省湖州市2014高考英语阅读理解一轮（暑假）精炼（9）含答案

★ 湖南省岳阳市2014高考英语一轮单项选择训练题（17）及答案

★ 2014高考英语（新人教版）一轮基础训练（18）A、B卷（附答案或解析）

★ 2017届高考英语二轮复习课时训练：14（含解析）

★ 2017高考四川省广安市英语阅读理解一轮系列训练：2（含解析）