When a psychologist does a general experiment about the human mind, he selects

people______ and asks them questions.

A.at length       B.   at random       C. in essence       D. in bulk

答案：B

参考译文:心理医生在对人脑进行一般性实验时，随即选择实验对象进行提问。

解析:

at length: 详尽地，最后

eg: I arrive in that city at length. 我最终到达了那个城市。

at random: 随机地，随便地

eg: The librarian took a book at random from the shelf. 图书管理员从书架上随便拿了一本书。

in essence: 实质上

eg: The two arguements are in essence the same. 这两个论点大致相同。

in bulk: 散装地，大量地

eg: It is more convenient to transport the goods in bulk. 散装运送货物更方便。