单词	F2 layer
释义	F2 layer noun ˈef-ˈtü-  : the upper of the two layers into which the F region of the ionosphere splits in the daytime at varying heights from about 120 miles (200 kilometers) to more than 300 miles (500 kilometers) above the earth Word History First Known Use 1933, in the meaning defined above
随便看	take against take aim take aim at take apart take as a sign take as given take as gospel take as read take aside take attendance take away take away from take away from (something) take away from something take back take board take by storm take by surprise take care take care of take care of business take center stage take chances take coals to newcastle take cognizance of

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