有趣的长难句29
昨天的正确答案是D，小伙伴们答对了吗？昨天的答案里有个小陷阱，由于受到周遭环境的影响，沉积物的物理或化学物质发生了变化，通过观察这些变化，人们可以推测当时的天气情况，因此，B答案里有个“in order to”的误导，人们观察沉积物的物质变化不是为了推断气候的变化，而是因为气候变化被记录在了沉积物的物质变化中，人们才去观察沉积物的。行为和目的颠倒，是这个考题的难点。
今天的题目选自《Orientation and Navigation》，迁徙鸟类的定向和定位的本领一直令研究者感到惊奇，一些科学家会捉些鸟儿进行这方面的实验，他们想找出鸟儿的导航仪和指南针。一些研究者说鸟儿定向是白天靠太阳，夜晚靠星星。也有一些研究者说没有太阳也没有星星的时候，鸟儿靠南北极的地磁力导航。迁徙鸟儿千百年来将定向和定位的本领代代传递下来，也是自然界的奇迹。
He then set up experiments with caged starlings and found that their orientation was, in fact, in the proper migratory direction except when the sky was overcast, at which times there was no clear direction to their restless movements.
Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?
A. Experiments revealed that caged starlings displayed a lack of directional sense and restless movements.
B. Experiments revealed that caged starlings were unable to orient themselves in the direction of their normal migratory route.
C. Experiments revealed that the restless movement of caged starlings had no clear direction.
D. Experiments revealed that caged starlings' orientation was accurate unless the weather was overcast.
ABCD四个答案哪个是正确的？解答长难句，锻炼理解力。
