第18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:at random意为“胡乱地,随便地”;at length意为“最后,详细地”;in essence意为“本质上,大体上,其实”;in bulk意为“散装,大批”。根据题意,B项为正确答案。