磁浮子液位计要定期对连通器导管进行()保持磁性浮子活动自由,磁翻板要定期打黄油让其活动自由 ["A、更换","B、清洗","C、检修","D、润滑"]
PGSM模式下共()个频道,中心频道为()。 ["62,31","124,62","186,93","248,124"]
到2015年,全国红色旅游年出行人数突破()亿人次,占国内旅游总人次的比例提高到四分之一。 ["8","9","10","11"]
玻璃管液位计要定期对玻璃管内部进行(),保证玻璃管的清洁,防止玻璃管被损坏 ["A、清洗","B、更换","C、检修","D、重新刻度"]
湖泊颗粒碳酸盐岩沉积类型.
煤矿透水有哪些危害?