backfinn.后脊(夹层；轧件舌尖；裂缝)backn.后面；背脊；靠背；后背；后卫vt.支持；后退adv.向后地adj.向后的；后面的；偏远的；过时的；积欠的backhoe excavator反铲挖掘机backing a warrant[法] 背书逮捕状back etching type背空腔型back incline body后倾体back to back loan背对背贷款back-off system补偿系统backing-up tank预真空箱back- scattering后向散射back-reef facies礁后相backplane material背板材料

1. Backsweep can improve the efficiency at the expense of surge margin.
   后掠会增加效率，但是会降低喘振裕度，而前掠有相反的趋势。