Among those methods of ensuring the supply of liquid fuel, shale oil is a realistic energy substitute for petroleum.

在保证液体燃料供应的诸多办法中，页岩油是一种较现实的石油替代能源。

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A thin oil distilled from petroleum or shale oil, used as a fuel for heating and cooking, in lamps, and as a denaturant for alcohol.

煤油从石油或页岩油中提取的一种稀油，用于加热或做饭的燃料，也用于点油灯和做酒的。

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A black or dark brown shale containing hydrocarbons that yield petroleum by distillation.

一种黑色或深褐色的页岩，含有碳氢化合物，通过提炼可产石油。

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Royal Dutch Shell said it has signed its first-ever production sharing contract for shale gas in China with state-owned China National Petroleum Corporation (CNPC).

BBC: Shell signs first shale gas production pact in China

Oil shale and tar sands are other sources of liquid fuel that are harder on the environment than petroleum.

NPR: Will Pricey Fuel Prompt Greener Energy Habits?