medium hard strata

hard and massive strata

hard kaolin (kaolinite) in coal measures strata

Hard Loess Strata

medium hard rock strata

shallow depth hard overlying strata

Hard Roof and Hard Coal

Hard Roof and Hard Floor

(semi) hard process

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

Abnormal hard tissue formation in pulp

abrasion-resistent plate by hard bead welding

Acicular hard coke

acid coagulated hard cheese