前面就是表示祈使句,表示動(dòng)作.后面卻是省略了主語(yǔ),因?yàn)樵赽efore后 所以加ing
就這樣為什么在before后就加ing?before doing sth 做某事之前 （完全正確的用法）例句與用法 1. We must have a plan before doing any work.做任何工作前，我們必須訂好計(jì)劃。2. We all should warm up before doing some exercises.開(kāi)始做運(yùn)動(dòng)前，我們都應(yīng)該熱身。3. He always consulted others before doing anything .他做什么事情都先和別人商量。4. Take your time to reflect before doing important things.在做重大的事情之前要從容不迫地思考一下。