12阀紧急二段阀是为了区分列车后部车辆的充气作用与列车前部车辆的减速充气作用。
You issue this SQL command to perform an online backup of the USER_DATA tablespace：ALTER TABLESPACE user_data BEGIN BACKUP；Next， you issue an operating system command to back up user_data01.dbf， the file that belongs to the USER_DATA tablespace. You then experience an instance failure. Which three statements are true？（） ["A","B","C","D","E"]
发展经济学在形成时期主要有哪些基本论点（） ["强调物质资本积累的重要性与必要性","强调工业化的重要性和必要性","强调市场的重要性与必要性","强调计划化的重要性与必要性"]
（）为集中养分供应，每株选留1～2个发育好的幼瓜，其余花果一律除掉。 ["西瓜","番茄","苦瓜","黄瓜"]
1988年被授于“《今天》文学奖”的诗人是（） ["舒婷","北岛","顾城","多多"]
计算机按照工作原理进行分类可以分为（）和（）。
