Skeptics argue,however, that rising temperatures and warmer oceans are part of a natural cycle and are not convinced the changes are a result of man's pollution.

VOA: standard.2009.05.03

And one of the things you often hear about in this discussion is about our oceans and about rainforests, and part of the reason why people want to protect those areas is because you find a lot of natural products in those regions.

其中你们会经常听到的一个,就是关于海洋和热带雨林的讨论,人们想保护这些地方的部分原因,就是因为在这些地方,人们可以发现一些天然产物。

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Other people think and feel that it's more of a natural part,

其他人觉得这只是个很自然的问题，

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Skeptics say global warming is part of a natural cycle of climate change.

VOA: standard.2009.12.09

Irons is part of a team with the Illinois Natural History Survey.

VOA: standard.2010.07.20

But the decision to hold most of the exercise in Kitgum has raised questions as to whether Natural Fire 10 is part of preparations for a renewed military effort against the Ugandan rebel group, the Lord's Resistance Army.

VOA: standard.2009.10.20