Question

【题目】 (2017·北京卷) ______ birds use their feathers for flight, some of their feathers are for other purposes.

A. Once B. If C. Although D. Because

Answer 1

【答案】C

【解析】试题分析：A. Once 一旦 B. If 如果 C. Although 尽管 D. Because因为。句意：尽管鸟儿们用羽毛来飞翔，但是他们的一些羽毛还有其他用途。根据语境可知前后之间是让步关系，故选C。