Back filling at abutment back of Bridge or culvert
back reaming and back transportation
Back-to-Back
对头拼接
背靠背
背对背的
背靠背结构
背对背
紧接的
背向式计数器
(pressure)gauge with back connection
a back stationary flat system with suction device
a basket carried on the back
A Dream Back To Qinghe River