题目

阅读理解D    The deserts of the world are not all covered with sand. Many of them have surfaces of rock or clay(黏土) or small stones. They are not flat, either. They often have high hills and deep valleys. There is some plants’ life in many parts of the desert. There is little rain in the desert, but it does fall often enough for most plants.    The deserts of the world are not uninhabited(无人居住的). People also live outside oases(绿洲), but these people are not farmers. They have camels, goats, donkeys, sheep, etc. These animals can live on the desert plants and do not n化合物C和E都是医用功能高分子材料，且组成中元素质量分数相同，均可由化合物A(C4H8O3)制得，如下图所示。B和D互为同分异构体。试写出：化学方程式A→D___________________，B→C___________________。反应类型：A→B________________，B→C_________________，A→E___________________，E的结构简式___________________。A的同分异构体(同类别有支链)的结构简式：___________________及___________________。