What are the problems of oil lamps according to Paragraph 1?

根据第一段，油灯存在哪些问题？

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The villagers were forced to use oil lamps, which are not only expensive but also dangerous because of the harmful gases they produce.

村民们被迫使用油灯，油灯不仅昂贵，而且它们所产生的有害气体十分危险。

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In ancient China, people used oil lamps at night.

在中国古代，人们晚上使用油灯。

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Many families use kerosene oil lamps.

VOA: special.2009.12.21

John Davidson Rockefeller - the founder of the Rockefeller empire - went to China and gave away oil lamps for free.

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Mindful markets and civil society will complete it as inexorably as innovators and capitalists got America off whale-oil lamps in the 1850s.

CNN: Freeing America from its addiction to oil

Several early 16th-century cast-metal oil lamps are modeled as African heads whose features, especially the mouths grotesquely stretched into wick-holders, convey a sense of mockery.

WSJ: Less Familiar Faces | Revealing the African Presence in Renaissance Europe | Princeton University Art Museum | By Barrymore Laurence Scherer