什么是群控？主要目的是什么？
参考答案：
为提高运行效率，节省能耗，减少乘客的平均待梯时间而将同一建筑中安装在一起的多台电梯进行统一控制即为群控。
– What a nice model ship!
– Thank you. It _________ me a few days to make it.
A．paid
B．spent
C．took
D．tried
-Which city has _________population, Beijing, Guiyang or Xingyi?
-XIngyi, of course.[ ]
A. the largest
B. the smallest
C. the most
D. the least
