In drilling an oil well, mud is used to lubricate the cutting bit.钻油井时, 泥浆被用来润滑钻头....

n.钻头...

cutting bit的音标：cutting bit的英式发音音标为：['kʌtɪŋ bit]cutting bit的美式发音音标为：['kʌtɪŋ bɪt]...