第27题: [单项选择]{{U}}Attempts{{/U}} have been made for nearly three decades to increase the amount of precipitation from clouds by seeding them with salt or silver iodide. A. Devices B. Hypotheses C. Efforts D. Suggestions 参考答案:C 答案解析:[分析] 名词辨析。
attempt努力,尝试:abandon the attempts放弃尝试。device装置:a device for opening bottles一个打开瓶子的装置。