第15题: [单项选择]In the flint decades of the twentieth century, the individual gem could not be seen, but could be worked with fruitfully. A. blindly B. completely C. productively D. carefully 参考答案:C 答案解析:blindly盲目地，摸索地；completely十分地，完全地；productively有结果地，有成果地； carefully小心地，谨慎地；fruitfully产量多地，肥沃地。
