A sudden drop in supplies of certain chemicals could knock the bottom out of the engineering industry.某些化学品供应的突然减少会造成工程行业的不景气。The rise in mortgage rates really knocked the bottom out of the housing market.按揭利率上升确实严重打击了房产市场。The new law knocked the bottom out of his investment almost overnight.这条新法律几乎一夜之间使他的投资荡然无存。