“crown block”的概念、定义、翻译、参考文献-科学参考

单词	crown block
释义	crown block [`krau̇n ´bläk] ^{PETROLEUM ENGINEERING} A wooden or steel beam joined to the tops of derrick posts of an oil well to support pulleys.
随便看	Fraude's reagent fraunhofer Fraunhofer corona Fraunhofer diffraction Fraunhofer lines Fraunhofer region Fraunhofer spectrum Frazer-Brace extraction method frazil frazil ice freckle Fredholm determinant Fredholm integral equations Fredholm operator Fredholm theorem Fredholm theory free admittance free air free-air anomaly free-air gravity anomaly free-air ionization chamber free-air temperature free ascent free association free atmosphere

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