1·Kramer surmised, therefore, that they were orienting according to the position of the Sun.
因此，克雷默推测，他们是根据太阳的位置来确定方向的。
2·Kramer initiated important new kinds of research regarding how animals orient and navigate.
克雷默开创了一类重要的新研究，是关于动物如何定位和导航的。
3·In another set of experiments, Kramer put identical food boxes around the cage, with food in only one of the boxes.
在另外一组实验中，克雷默在鸟笼周围放置了完全相同的食盒，这些食盒中只有一个食盒有食物。
4·Early in his research, Kramer found that caged migratory birds became very restless at about the time they would normally have begun migration in the wild.
在克雷默早期的研究中，他发现被关在笼中的候鸟在它们通常开始在迁徙的大致时间会变得非常不安。
5·The question perplexed people for years, until, in the 1950s, a German scientist named Gustave Kramer provided some answers and, in the process, raised new questions.
这个问题困扰了人们多年，直到20世纪50年代，一位名叫古斯塔夫·克雷默的德国科学家给出了一些答案，并在此过程中提出了新的问题。