二等水准测量
second-class leveling
the Second Order Leveling
second-class standard of measurement
二等水准网
The second grade level net
second-class level web
三、四等水准测量
3、4 order leveling surveying
特殊抽样水准等级
S I-S IV Special I-Special IV
一、二等水准测量
first and second order leveling
一等水准复测
first order leveling resurvey
高-高准位浮筒开关
high-high level float switch
高水高排
high water level and high-speed drainage
高水准虚拟容器
HOVC High Order Virtual Container