求翻译：世界观察研究所最近发表的一份研究报告指出,为了使城市街道更安全,交通更顺畅,空气更清洁,自行车将成为廿一世纪城市重要的交通工具之一。是什么意思？

The Worldwatch Institute recently published a research report that, in order to make the city streets safer and smoother traffic, cleaner air, the bike will be the city of the 21st century, one of the important means of transport of.

World Watch Institute recently published a study that, in order to make city streets safer and more smoothly, and the air traffic more clean, bicycles will be a 21st Century City Transport in the capital.

The world observation research institute published recently a memoir pointed out, in order to cause the city street to be safer, the transportation was smoother, the air was cleaner, the bicycle will become one of 21 century city important transportation vehicles.

A study recently published by the Worldwatch Institute report pointed out that, in order to make the city streets safer, more smooth, air cleaner, bicycle one of the important means of transport will become the 21st century city.

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