The most obvious reason for optimism is the plunge in energy costs. Not only has the price of oil halved in the past six months, but natural gas is the cheapest it has been in a decade, bar a few panicked months after Lehman Brothers collapsed, when the world economy appeared to be imploding.

我不明白之处在于：“but natural gas is the cheapest ”和“it has been in a decade”之间是怎么连接的，这应该是个复合句了，但是引导词没有啊，引导词是省略了么？~谢谢回答者

文章来自经济学人150117。

翻译：乐观的最明显理由是能源成本的大幅下降。不仅油价在过去的6个月中跌去了一半，天然气的价格也是十年中最便宜的时候，而这种情况只在雷曼兄弟倒闭后人心惶惶的那几个月中出现过。

句中bar按照except来理解，该用法仅在书面表达中使用。