名词
中文翻译：重油
同义词：
['heavy crude oil', 'heavy petroleum', 'heavy bitumen例句：1. The heavy oil is difficult to refine.（重油难以提炼。）']
例句：
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1. The heavy oil is difficult to refine.
重油难以提炼。
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2.Heavy oil is a source of energy for many countries.
重油是许多国家的能量来源。
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3. The heavy oil industry has been struggling with environmental issues.
重油行业一直面临着环境问题。