【题目】 at the back of the classroom several old professors, listening attentively to the new teacher.
A. Seated; were B. Seating; was
C. Sat; were D. Sitting; was
在线课程【答案】A
【解析】考查过去分词和主谓一致。句意：坐在教室后面的是几位老教授，正在认真地听新老师讲课。several old professors是句子主语，复数形式，谓语动词用were；be seated坐下，表示地点的状语位于句首，句子用全部倒装，过去分词提前，故选A。