frozen earth engineering

frozen earth exploration

frozen earth storage

frozen earth temperature field

key bed of frozen earth

Maximum frozen earth depth

Perennial frozen earth

pile and frozen earth

Seasonal frozen earth

water and salt of frozen earth

Earth Roadbed

Soft earth roadbed

boundary line of two times between earth excavation area and earth fill area

Earth Day [first Earth Day in 1970]

annually frozen layer

anti-frozen

artificial frozen soil

Artificial insemination of frozen semen

artificially frozen ground