题目

阅读理解 A team of over 30 Chinese surveyors left thebase camp at Mount Qomolangma for a higher spot on its journey to the peak onWednesday as part of the country's mission to remeasure the height of the world'shighest mountain.The remeasurement of the peak's height is a part of China's latestlarge-scale scientific survey of Qomolangma. Preparation of the project wasstarted in early March, with 53 surveyors from the First Geodetic SurveyingBrigade (大地测量旅) getting stationed nearQomolangma to carry out adaptive climbing and training in other technicalskills, and they are going to t已知甲、乙为两种黑色粉末，丙是一种红色固体，丁为一种蓝色溶液的溶质，A是一种能使澄清石灰水变浑浊的气体，它们的相互转化关系如图所示．请用正确的化学式填空：A是______，甲是______，丙是______，丁是______．