sight glass
观察镜
观察窗
显示玻璃
玻璃液位计
玻璃液面计
窥视镜
视镜
窥镜
检视窗
量位计
cinnamon oil cassia oil
Essential oil Volatile oil
Extract Oil of Lubricating Oil
oil bearing sewage in oil field8
Oil Extractor in Oil Field
oil shale and oil shale residue
ultraheavy oil as fuel oil
“Four delicacies”in chicken oil
150000DWT suez crude oil carrier
17% cut oil consumption 17%