简述发电机的作用。
下列（）应计入建设项目前期工作费。 ["A.编制工程可行性研究报告所需费用 ","B.初步设计的勘察费 ","C.水土保持评估费 ","D.设计文件审查费"]
If authentication is enabled，which statement is true？（） ["client reports will display authenticated usernames","client reports will display both the username and IP address of the clients","client reports are not affected by authentication","client reports will display the IP address of the authentication server"]
The dispersion of a non-zero dispersion shifted fiber is 6 ps/nm*km at 1550 nm and 10 ps/nm*km at 1610 nm. What is the minimum dispersion compensation required if an L-Band DWDM signal travels through 200 km of fiber and has a dispersion tolerance of 1800 ps/nm?（） [" none"," -600 ps\/nm"," -200 ps\/nm"," +200 ps\/nm"," +600 ps\/nm"]
将游戏划分为机能游戏、想象游戏、制作游戏和接受游戏，其划分的依据是（） ["按儿童在游戏中的体验形式分类","按游戏的教育作用分类","按游戏的关键特性分类","按儿童在游戏中的社会行为表现分类"]
区域亚文化理论
