________ birds use their feathers for flight, some of their feathers are for other purposes. A.Once ...
2022-07-05 12:09:06 122次 天津市西青区2019-2020学年高二上学期期末英语试卷 单项填空 反馈错误 加入收藏 正确率 : 100%
题目内容：
________ birds use their feathers for flight, some of their feathers are for other purposes.
A.Once B.If C.Although D.Because
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