hub n. 毂，木片，中心
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1.the central part of a wheel, rotating on or with the axle, and from which the spokes radiate.
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2.the effective center of an activity, region, or network."the city has always been the financial hub of the country"
20170309词
身是菩提树，心如明镜台，时时勤拂拭，勿使惹尘埃。