单词	F region
释义	F region noun : the highest region of the ionosphere occurring from 80 miles (130 kilometers) to more than 300 miles (500 kilometers) Word History First Known Use 1923, in the meaning defined above
随便看	play both ends against the middle play by ear play cat and mouse play catch-up play close to one's chest play close to the vest play coy play Cupid play dead play debt play doctor play down play ducks and drakes with play fair play fast and loose play fixer play footsie play for laughs play for time play forward play games play God play gym play hard to get play hell with

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