HALT PIPE在海洋石油里是什么东西？ a half-pipe is a structure used in gravity extreme sports such as snowboarding , skateboarding , skiing , freestyle bmx , and inline skating . the structure is wood, concrete, metal, earth, or snow. it resembles a cross section of a swimming pool, essentially two concave ramps (or quarter-pipes ), topped by copings and decks, facing each other across a flat transition. originally half-pipes were half sections of a large diameter pipe. since the 1980s, half-pipes contain an extended flat bottom between the quarter-pipes; the original style half-pipes are no longer built. flat ground provides time to regain balance after landing and more time to prepare for the next trick. 详细的你看 http:///wiki/half_pipe 查看更多
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