Under the current laws of physics, it is difficult to understand how it could exist. And this is probably the main reason scientists dismissed it for so long.

就现有的物理学定律，我们很难理解球状闪电存在的原因，而这可能也是长期以来科学家忽视球状闪电的主要原因。

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Traveling on a nearly circular, 229-day orbit around both host stars, the planet lies outside the system's habitable zone—the region where liquid water, and thus life as we know it, could exist.

它的运行轨道为近似的圆形，以229天为周期，围绕着两个恒星作轨道运行，这个行星位于这个系统的可居住区之外——所谓可居住区，那里有液体水，正像我们所知道的那样，那里可能会有生命的存在。

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Clay answered that no power on earth could force him to vote to establish slavery where it did not exist.

VOA: special.2009.03.19

Now, of course, it could still be that in the real world the one thing cannot exist without the other.

还是可以说,在真实世界里,某物不能脱离于另一物而独立存在

耶鲁公开课 - 死亡课程节选

As I said, it looks as though to answer the question, "Could I continue to exist after the death of my body?"

如我所讲,似乎要回答这个问题,就得回答"肉体死后我能否继续存在"

耶鲁公开课 - 死亡课程节选

The actual evidence for global warming (GW) itself over the last century is thin but it could exist.

FORBES: Peter Gleick Sets Back the Climate Debate

Alexander contradicted Schmidt, saying that he thought it could exist, but punted on the second question about definition.

FORBES: General Alexander's Confirmation And The Failure Of Cyberwar Transparency

Astrobiologists like the idea that life can be built with a completely different set of chemical building blocks because it means that life could then exist in all sorts of places that Earth-based living things would find intolerable.

FORBES: Why Those Cool Arsenic Bacteria Are Not A New Form Of Life