If astronomers could observe metallicity gradients in spiral galaxies billions of light-years away, we could see how steep the gradients were billions of years ago and thus how they change over time.
如果天文学家能够观测到十亿光年外的螺旋星云的金属丰度梯度，我们就可以知道亿万年之前的梯度有多大，因此也就可以知道它是如何随时间变化的。
By exploiting a lucky accident, astronomers have for the first time measured a key property of a spiral galaxy located more than nine billion light-years away.
通过一个偶然的机会，宇宙学家们第一次测量到了九十亿光年之外某个螺旋星系的一个关键性质。
One of the efforts people are making to try and reduce the amount of energy they use is to replace their old light bulbs with the new spiral compact fluorescent kind.
人类为了减少能源消耗所做的努力之一便是用新的螺旋紧凑型荧光灯来换下他们的旧灯泡。
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