Why isn't there more variety of life on Earth?

为什么地球上没有更多不同种类的生命形式？

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She is also an extraordinary evolutionary planet, with a marvelous variety of life.

她是一个非同寻常的进化行星，有着极其多样化的生命。

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The frozen seas here are a harsh realm to explore, but they're anything but bleak, sustaining a variety of life above and below.

这里的冰冻海洋是严酷的探索领域，但并不荒凉，维持着海面上下各种各样的生命。

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"Being physically active on a regular basis is a difficult thing, but the MyActivity Pryamid offers adults a variety of ways that they can reach these recommendations for health and improving the quality of life."

VOA: standard.2010.02.26

Of course that person has as much variety of life as you and I do.

当然，这些人和我们一样,他们的生活也是充满变化的。

普林斯顿公开课 - 人性课程节选

As you will see, it is a way in which you represent a variety of things about your own life.

你将会看到，你通过它展现,你生活中的方方面面。

麻省理工公开课 - 媒体、教育、市场课程节选

The world is invited to take action in 2010 to safeguard the variety of life on earth: biodiversity.

UNESCO: International Year of Biodiversity 2010

He is searching also for other therapeutic gases, in experiments on a variety of life forms ranging from yeast to pigs.

FORBES: Magazine Article

Trudy, a crazy bag lady, has taken upon herself the task of showing visiting extraterrestrials the variety of life on earth.

NEWYORKER: Search for Signs of Intelligent Life in the Universe