第15题: [单项选择]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 参考答案:B 答案解析:题意是:当一个心理学家做一个关于人类心理的一般实验时,他 ______ 选择人群并问他们问题。[B] at random“随机地”,符合题意。[A] at length“终于,详尽地”,[C] in