“expanding arm”的概念、定义、翻译、参考文献-科学参考

单词	expanding arm
释义	expanding arm [ik`spand·iŋ `ärm] ^ASTRONOMY A spiral arm of the Galaxy consisting of neutral hydrogen that lies between 2.5 and 4 kiloparsecs beyond the galactic center and is moving out from it at about 85 miles (135 kilometers) per second.
随便看	course-line deviation indicator course-line selector course made good course over the ground course programmer course recorder course scalloping course softening courseware coursing joint Couvinian covalence covalent bond covalent crystal covalent hydride covalent radius covariance covariance analysis covariant covariant components covariant derivative covariant equation covariant functor covariant index covariant tensor

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