[解析]
(1)B.细节理解题。根据第二段的Dr.Ciprian Ardelean,of the Autonomous University of Zacatecas who led the groundbreaking re﹣ search,first became aware of the cave in May 2010.(萨卡特卡斯自治大学的西普里亚安•阿德里安博士领导了这项开创性的研究,他于2010年5月首次发现了这个洞穴。)和However,Dr.Ardelean and his team found enough clues to make the difficult journey three additional times﹣in 2012,2016,and ﹣2017.( 然而,阿德里安博士和他的团队找到了足够的线索,进行了三次额外的艰难的旅程﹣﹣﹣﹣在2012年、2016年和2017年。)可知,阿德里安博士第一次去这个洞穴是在2010年5月,然后在2012,2016,2017年又去 了三次,故他探索了这个洞穴四次,故选B。
(2)C.细节理解题。根据第三段The archeologists' efforts revealed many artifacts including over 1,900 stone tools from multiple layers of the cave.The scientists found that most of the tools were between 16,000 and 13,000 years old.However,239 artifacts unearthed from the deepest layer of the cave dated back an astonishing 30,000 years!(考古学家的努力发现了许多文物,包括1900多件来自洞穴多层的石器。科学家们发现,大多数工具的历史都在1.6万到1.3万年之间。然而,从洞穴最深处出土的239件文物可以追溯到令人吃惊的3万年前! )可知,从洞穴最深处发现的石器动摇了关于北美的传统想法。故选C。
(3)D.词义猜测题。根据划线句上文We don't know who they were,where they came from or where they went.(我们不知道他们是谁,他们从哪里来,他们去哪里。)可知,科学家们不了解古代人类的情况,因此推断划线句They're a complete enigma.句意是说:他们完全是个谜。故划线词词义与.D项"Mystery(谜)"意思相近,结合选项A.Problem.问题;B.Breakthrough.背景;C.Appeal.呼吁;D.Mystery.谜。故选D。
(4)A.文章出处题。通读全文并结合第一段中的Now,evidence from the Chiquihuite Cave in Zacatecas,Central Mexico,seems to suggest that prehistoric humans may have been living in North America as early as 30,000 years ago.(现在,来自墨西哥中部萨卡特卡斯州基奎维特洞穴的证据似乎表明,史前人类可能早在3万年前就生活在北美。)可知,文章介绍了一项考古发现,因此最有可能在报纸的考古学栏目读到这篇文章。结合选项A.Archaeology.考古学;B.Anecdote.轶事;C.Economy.经济;D.Literature.文学。故选A。