正常时空气中含氧量为21%，含氧时（）是人们工作最低要求，含氧量（）是人们安全工作最低根限 ["19%","20%","15%","16.7%"]
继电器按动作时间可分为（）和（）。
Your boss at Certkiller .com wants you to clarify Oracle 10g. What statement about the Shared Server configuration is valid？（） ["A","B","C","D"]
以下属于公路工程造价领域的设备的是（） ["A.木扒杆 ","B.满布式钢管支架 ","C.单导梁 ","D.龙门架"]
Which phase includes testing operational processes and procedures in accordance with the Cisco Unified Communications operations plan（） ["Operate","Design","Deploy","Implement"]
影响滚动摩擦的因素
