The crust eventually becomes a rigid roof, forming a lava tube.
地壳最终成为一个僵化的屋顶，形成了熔岩管。
This paper aimed at the injection forming of a kind of thin and long plastic tube, and it also gives a successful example of one mould for four parts and loop injection.
针对一种细、长且薄的管状零件的注塑成型，给出了一种一模四件、环形浇注的成功实例。
The purpose of perforation is penetrating the casing tube, cement sheath and a certain depth of the formation and forming unhindered channels for oil and gas flowing into the well casing.
射孔目的就是射穿套管、水泥环和地层内一定的深度，为地层的油气流入至井筒，形成一个顺畅的通道。
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