In some parts of the world, cyclists have been powering safety lights for years with devices called bicycle dynamos, which use a generator to create alternating current with every turn of the wheels.

在世界的一些地方，骑自行车的人已经通过叫自行车发电机的装置产生了多年的安全电能。当自行车车轮转动的时候一个装在上面的发电机就会产生交流电。

youdao

In the early years of the 19th century, farmers in western Pennsylvania kept their wagon wheels greased with puddles of bubbling muck that studded the countryside.

在19世纪早期，西部宾夕法尼亚州的农民都给自己的马车轮子抹上乡下随处可见的气泡肥料胶土。

youdao

The Camaro has 20-inch wheels, which were nearly unheard of on mass-market cars a few years ago.

Camaro的车轮有20英寸，几年前这在大众市场上还是闻所未闻的。

youdao

The Fed chief expressed empathy with the challenges of cutting government deficits while trying to promote growth, acknowledging the complex challenge facing policymakers, but renewed his push for Congress to pick up the ball and run with it after the Fed has spent three years trying to grease the wheels of recovery.

FORBES: Bernanke Warns Congress: More Sluggish Job Growth Ahead

Ruts cut by hundreds of years of wagon wheels can be seen in the stone gateways of forts.

BBC: Walking Hadrian��s Wall

Twenty years ago, the wheels of rail privatisation were set in motion.

BBC: Have train fares gone up or down since British Rail?