暗能量占据了我们宇宙的四分之三，然而又是完全看不见的。我们只能根据它对宇宙膨胀所起的作用来认识到它的存在。
Dark energy makes up three-quarters of our Universe but is totally invisible. We only know it exists because of its effect on the expansion of the Universe.
最上面比较暗的冰层是去年冬天的雪，而中间比较亮的部分形成于去年夏天，最底部比较暗的部分又是更早一年冬天的雪。
The uppermost dimmer layer is snow from last winter, the bright layer in the center is last summer, and the dimmer layer at bottom is the winter before that.
有一天，天空突然暗了下来，又是刮风，又是打雷，又是下雨，真龙飞到了叶公的家里。
One day, the sky suddenly darkened, and then came wind, thunder and rain. The real dragon flew to Ye Gong's home.
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