bottomer井底把钓工bottomn.底部；底端adj.底部的v.触底；打(基础)bottom-up strategy自底向上策略bottom weather strip车窗下挡风胶垫bottom slab creaking底板崩裂bottom standing wave底层驻波Bottom trawl fishery底拖网bottom out bottom up倒置； 反转bottom plate leakage底板渗漏bottom-dump haulet底卸拖运车bottom-hole bumper井眼底部减震器bottom valve failure底阀泄漏