pass down the line book {= PDL book}
rare book good edition scare book
register book [= registered mail book]
silverfish book-louse book-worm
book lungs. lung book(s)
air pocket
气袋
气囊
气穴
气阱
气龛
气潭
空气袋
气泡
气坠
气窝
电磁信息泄漏
气陷
air pocket hand-type brake
algebraic logic of pocket calculator