Sandstone and limestone are the main targets cut by oil and gas well drilling and for their physical mechanical property there have been systematic determination method and quantitative gradation.
砂岩和石灰岩是石油天然气钻井破岩的主要对象，它的物理力学性质已有系统的测定方法和定量分级。
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This exquisite rhodium-plated necklace features an emblem with a Vintage Rose crystal in the Oval cut and shimmering crystal pavé in a gradation of crystal colours.