单选题
Recent research from animal behaviorists suggests that "as the crow flies" should no longer be taken to mean "the shortest distance between two points. " Zoologists at Oxford University,【C1】______conducted an eighteen-month【C2】______of homing pigeons, have concluded that under some circumstances, pigeons follow【C3】______visual landmarks to find their way home【C4】______than taking the shortest, most direct route.【C5】______for their ability to navigate long distances, homing pigeons use the【C6】______of the sun and stars, their inbuilt compasses, and perhaps also their sense of smell to direct their flight over long【C7】______or on a journey for the first time.【C8】______, different factors appear to affect a pigeon's navigation【C9】______it is released close to its【C10】______. Animal behaviorists reached this【C11】______after attaching small global positioning devices to the backs of pigeons and releasing them a few miles from their home. These devices enabled the scientists to【C12】______the precise location of each pigeon every second of【C13】______flight. Each pigeon was tracked for approximately twenty flights from the【C14】______point. For the first several flights, each bird's path【C15】______significantly from the paths it had taken【C16】______Subsequently, 【C17】______, the bird would tend to follow the same path, 【C18】______after flight, even though that path was not always the most direct route home. The scientists concluded that pigeons use a【C19】______of familiar visual landmarks to find their way when they are near their home rather than relying primarily on compass navigation. Major highways are one【C20】______landmark. Almost comically, some of the pigeons followed the path of a major highway they could see below them, turning where the road turned, and even following the circular path of the exit ramps.
单选题
【C1】
【正确答案】
C
【答案解析】解析：本题考查定语从句，后面的“conducted an eighteen—month”是对前面Zoolo—gists的修饰，而Zoologists指牛津大学的动物学家，因此，先行词应该是与人相对应的，因此应为who。由此可知正确答案为C选项。
【答案解析】解析：对本题横线处的选择写需要结合整篇文章的意思，联系文章倒数第三句“Thescientists concluded that pigeons use a______of familiar visual landmarks”及全文意思可知，此处想要表达的是鸽子能够通过相似的地标来找到回家的路，因此本题横线处应填familiar，答案为B选项。