back panel [機] 后板back palm [藝術(shù)學(xué)]手背藏牌back painting [土木建筑工程]底面涂漆[材料科學(xué)]底漆back pain 背痛back pages 報紙的最后幾頁（一般是體育新聞）。back pad 小鞍back pack 背包式滅火器back overlap [紡織科學(xué)技術(shù)]后搭門back out of contract [地球科學(xué)]背棄合同義務(wù)back out of 收回（諾言等）；食言，背信back out loop [體育]后外結(jié)環(huán)形back out bracket [體育]后內(nèi)括弧形back out 退出；收回；食言，違約back orifice 2000 back orifice 網(wǎng)絡(luò)后洞back order cost [經(jīng)濟學(xué)]延遲交貨成本back opening door [交通運輸工程]后開門式back on track 重回正軌；重上軌道；改過自新back on their heels [航空、航天科學(xué)技術(shù)]被對手逼退back on 背靠