27.D。推断。根据倒数第二段中的I watched as movements such as#BlackInThelvorytook hold...After a series of meetings,faculty members decided to do away withthe qualifying exam structure...Students would be asked questions ..But theywouldn't face exclusion from the program可知,学生们不再被一场考试定义一他们不再因为一场考试而被剥夺成为一名科学家的机会。C篇主题语境:人与自然一自然生态本文是说明文。海洋很可能在大灭绝发生后的一百万年后就恢复了生机。28.C。推断。根据第一段中的It happened after a series of massive volcanic eruptionsaround 251.9 million years ago Life in the seas suffered.More than 80 percent ofmarine species went extinct.Some researchers have even proposed that entirelevels of the food web may have disappeared可知,大约2.519亿年前,海洋生态遭到很严重的破坏。29.B。理解具体信息。根据第二段中的he discovered a well-preserved fossil,whichwould later be identified as a primitive lobster和第三段中的The lobster's goodcondition led to a succession of repeated visits可知,Dai在贵阳发现了一块保存完好的化石,这使得他三番五次回到那里。30.A。推断。根据第四段中的According to Dai,,the fossils suggest that the roots oftoday's marine ecosystems took hold soon after the Great Dying可知,Dai认为那些化石表明,今天海洋生态系统的根基是在大灭绝之后不久形成的,也就是说,海洋生物在大灭绝后不久就恢复了生机。31.C,推断。根据第一段中的The oceans warmed significantly和最后一段中的And past