buckle down片语动词KK [ˋbʌkəl daʊn] /ˈbʌkəl daʊn/发音片语动词1认真投入、全力以赴、专心用功口语If you buckle down now, you can finish the report by Friday.如果你现在认真投入,周五前就能把报告写完。用这个字练口说→