A Pittsburgh-based robotics and engineering startup recently unveiled Moonwalkers, a pair of battery-powered shoes that it     1     (claim) can boost walk speeds by up     2     250%.

At first glance, Moonwalkers look like a pair of futuristic roller-skates, but there is actually a lot more to them than that. You’re     3     (actual) meant to walk with them the way you would regular shoes or sneakers, letting the motorized wheels put a spring in your step.     4     (power)by a state-of-the-art brushless DC motor, this ingenious contraption is actually a platform     5     can be attached to a wide variety of footwear to significantly increase your walking speed up to a reported 7mph/11kph. For comparison, humans’ average     6     (walk) speed ranges from 2.5 to 4 mph. The sensation of walking with the world’s fastest shoes     7     (compare) to that of walking on a ‘moving walkway’ in     8     airport.

Designed by Shift Robotics, an offshoot of Carnegie Mellon University, Moonwalkers consist of a 300W brushless motor in each 4.2-lb (1.9-kg) shoe that powers eight polyurethane wheels. There is also an AI-powered gearbox that increases or decreases speed according to data regarding the wearer’s walk collected by a series of sensors. The shoes are also able to detect downhill movement to prevent accidents.

But do the world’s fastest shoes work     9     (sensor)     10     uneven terrain, or things like stairs? We all know how tricky those are to mitigate in rollerskates. Well, apparently the designers took that into consideration and implemented a simple gesture that allows the wearer to lock the wheels so that they can walk up or down stairs as they would in regular footwear.

The first folding fans were made around 1000 A. D. in China, and were brought to Europe by Portuguese traders in the early 1500s.

One type of folding fans     1     (compose) of sticks of identical length held together at the bottom with a curved leaf of paper, silk, lace or other materials glued to the sticks.     2     type of folding fan is the brisé fan,     3     (consist) only of decorative sticks with no pleased (起褶的) leaf.

The brisé fan was popular in the 17th and early 18th centuries, but was never as widespread as the folding fan with a painted and pleated leaf. However, in the late 18th and early 19th century     4     (small) fans had come into fashion, perhaps due to the narrower, high-waisted dresses that could no longer accommodate large pockets beneath,     5     one could put a large fan. The smaller fan, often     6     (call) “opera” size, could have     7     (easy) slipped into a handbag. Whatever the reason, smaller fans saw     8     increase in popularity during this period. The     9     (carve) of the brisé fan is so delicate that it can set some fashionable ladies apart     10     others in a party. They carried brisé fans to make their simplicity echo the general simplicity of dress.