题目

题型：不详难度：来源：

It is necessary to explain your theory _____, otherwise the audience won"t make sense of what you are trying to get across.

A．on purpose

B．at length

C．at random

D． on average

答案

B

解析

试题分析：句意：有必要详细地解释你的理论，否则观众就不会明白你想要表达的意思。A. on purpose故意地；B. at length详细地；C. at random随意；D. on average平均。故选B。
考点: 考查介词短语的用法。