Some already exist in Spain and a few more are on the drawing board for Nevada and California.

西班牙已建有一些类似的电厂，而美国内华达州和加利福尼亚州则正在规划兴建更多这样的电厂。

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As for academic research, some disclosure requirements already exist.

关于学术研究领域，一些中断关系的要求已经存在。

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More browsers will no doubt be created (and some may already exist), so consider the future as well.

肯定会有更多的浏览器被创造出来(已经有很多存在了)，所有为长远考虑一下。

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Some of these services already exist but have yet to hit the mainstream.

BBC: Viewpoint: The hyper-individual

It says in part that self-driving cars are closer than they appear because some of the prerequisites already exist.

FORBES: Cars That Can Drive Themselves Are Still A Ways Off; Cars That Can Stop Themselves Are Already On Sale

Oddly, it looks like the app selection is still missing some key titles that already exist on Windows Phone 7, but Samsung's made its own efforts, with preinstalled apps running the gamut from the useful (ChatON) to the less so (Samsung's own Music Hub).

ENGADGET: Samsung ATIV S: Hands-on with Samsung's first Windows Phone 8 device (video)