medium hard strata

HARD AND MASSIVE OVERLYING STRATA

hard and massive strata

hard kaolin (kaolinite) in coal measures strata

Hard Loess Strata

HARD-AND-THICK STRATA

medium hard rock strata

shallow depth hard overlying strata

Hard Roof and Hard Coal

Hard Roof and Hard Floor

hard-soft-hard sandwich media

(semi) hard process

20 m VERY THICK AND MEDIUM HARD SEAM

3 channels hard cholecystoscope

A Good Man Is Hard to Find

a hard case

a hard nut to crack

a hard row to hoe

a hard sphere unit