Sam is doing some ______ about the ancient Silk Road. A. exercise B. operations C. research D. exper...
2022-11-11 02:06:21 69次 2017年初中毕业升学考试（山东德州卷）英语（解析版） 单项填空 反馈错误 加入收藏 正确率 : 100%
题目内容：
Sam is doing some ______ about the ancient Silk Road.
A. exercise B. operations C. research D. experiments
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