Right knowledge has three sources: direct cognition, inference and the words of the awakened ones.

正确的知识有三个来源：直接的认知、推论和开悟者的话。

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These results show that the underground water has three sources, namely deep karst, shallow porous and surface waters.

结果表明，本区地下水有三个来源：深部喀斯特岩溶水、浅部孔隙水和地表水。

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Beijing railway has the original railway, every day through three pairs of conventional trains, a pair of train travel round-trip air-conditioned car in Beijing - brook sources.

铁路有京原铁路，每天有三对常规列车通过，一对旅游专列空调车往返于北京—涞源之间。

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Additionally, TechCrunch says it has three independent sources that confirm there's a large iPod touch is coming next Fall with a 7 or 9-inch screen.

ENGADGET: Apple rumor roundup: aluminum Mac minis and supersized iPod touches

The government has arranged it so there are just three sources that really matter for bond ratings the big-three credit rating agencies are effectively a government-approved oligopoly.

FORBES: At Odds Over S&P

Nuclear power has grown faster over the past three decades than renewable alternative energy sources, such as solar, wave, wind and geothermal power.

FORBES: Magazine Article