问题
单项选择题
The magician picked several persons ______ from the audience and asked them to help him with the performance.
A．by accident
B．at random
C．on occasion
D．on average
答案
参考答案：B
解析：[分析] 习语辨析。 A．by accident偶然；B．at random随便地，任意地，胡乱地：C．on occasion有时，D．on average平均起来；因此B为答案。