Smoking a lot of cigarettes can harm and even kill over a long period of time.

长期大量吸烟会危害身体健康，甚至导致死亡。

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Long-period comets,however, may take several hundred years to orbit the sun.

VOA: special.2011.02.09

Stocks have paid 4% more a year over this incredibly long time period than short-term bonds.

股票在相当长的一段时间里,每年都比短期债券投资收益率,高出4个百分点。

耶鲁公开课 - 金融市场课程节选

That's where I--once that gets going, it goes for a long period of time.

一旦开始了,就喋喋不休

耶鲁公开课 - 聆听音乐课程节选

After looking at the orbits of almost 300 long-period comets, they have concluded that too many are coming from particular parts of the sky.

ECONOMIST: X marks the spot

Long-period comets can arrive from any direction in space and are believed to originate in the Oort cloud (a reservoir of comets encircling the sun, the existence of which was worked out at the same time as the Kuiper belt by Jan Oort, a Dutch astronomer).

ECONOMIST: Unbuckling the Kuiper belt

Mr. O'CONNOR: The ICP technology involves drilling holes--vertical holes into the ground and inserting long electric heaters, which then gradually heat the rock over a long period of time, and over a long period of time--by that, I mean two or three or more years.

NPR: Industry Seeks to Extract Oil from Rocky Mountain Shale