Sandstones are, as a rule , interbedded with shales.砂岩通常都与页岩互层.This paper presents the PDC bits with the satisfactory testing result in the multi - interbedded formation.介绍了一种复合式PDC钻头,该钻头在多夹层地层钻井施工中取得了较好的试验效果.A shale for...
这些大机构总是随意制定规定，而且说变就变。These large institutions make — and change—the rules to suit themselves.条约规定他们必须尊重其邻国的独立。The treaty binds them to respect their neighbour's independence.警察如果遵守这些规定的话，一年都活不了。A policeman would not...