【正确答案】 B

【答案解析】解析：结构识别。expound on详细说明，解释：She expounded for some hours on her theories about Central America．她用了几个小时阐述中美洲。explain in detail详细解释：The matter will be explained in detail in a separate letter．此事当另函详陈。find fault with挑剔：She found fault with the arrangement of the furniture．她吹毛求疵地说家具摆得不对。outlined briefly略述；offered in published form以出版物的形式提供。