A type of vacuum pump that is used to achieve rough vacuum from initial atmospheric pressure.

simple past tense and past participle of prepay

Drawn or worked by a single horse. / (by extension) Small, insignificant.

A large alluvial plain of northern China, bordered to the north by the Yanshan Mountains, to the west by the Taihang Mountains and Funiu Mountains, to the southwest by the Dabie Mountains and Tongb...