bread and butter不只有面包和黃油的意思，還有(某人或公司的)主要收入來(lái)源；謀生之道。
【例句】
With domestic lending still its bread and butter, much depends on continued economic growth in China.
鑒于國(guó)內(nèi)貸款仍然是工行主要的收入來(lái)源，工行將在很大程度上依賴(lài)于中國(guó)經(jīng)濟(jì)的持續(xù)增長(zhǎng)。
Gardening is my bread and butter right now.
眼下園藝工作是我的謀生之道。