Urban public bike service isn’t a new phenomenon. Government-sponsored public bike systems have been introduced into many cities in China Mobike, a new kind of public bike rental service, started in Shanghai and has expanded to Beijing. People can use this service by scanning the QR code(二维码) on the bike to unlock the smart lock. The standard cost of this service is 1 yuan per 30 minutes. Users can pay with popular mobile payment methods such as Alipay and WeChat. Mobike now has more than 10, 000 bikes in Shanghai, allowing most riders to find a bike anywhere within a diameter(直径) of 300 meters. Many people ride a Mobike for a short trip, such as from home to the subway, subway to the work place or to a grocery store. Experts say Mobike is a good supplement(补充) to the public bike rental service since city people are now fond of “Green Riding”, and environmentally-friendly means of transportation. Just because of this, the company providing the service is increasing the number by hundred every day.

Driving on Ice

In many northern states, the winters are so cold that the lakes freeze right over. In Minnesotas, Michigan, and Maine, the ice in these lakes can freeze two to three feet deep.

When the ice is that thick, it becomes possible to actually drive a car or truck across the ice. While driving on ice sounds like something that people would do just for fun, a lot of people drive across frozen lakes for very practical reasons.

For example, there are people who live year­round on islands within these northern lakes. In the middle of winter the only practical way of traveling to the mainland is by driving across the frozen lakes.

Actually, when the lake is frozen two to three feet deep, this is a perfect opportunity for people living on islands to transport large objects onto or off the islands. Say, for instance, you owned a cabin on a small island in the middle of a lake in Michigan. Suppose you decided that you wanted to build an extra room onto the cabin.

Transporting all the building materials onto the island using a boat would take a lot of work and expense. But if you waited until winter, you could easily drive all the building materials across the lake.

How can you tell if a lake is frozen solid enough to drive on? The surest way to know is to wait until several other cars and trucks have safely driven across the ice.

It’s possible that one section of the lake has currents that prevent the lake from freezing solid. Or there might be a river or stream that brings slightly warmer water into one part of the lake. So even though most of the lake is frozen solid, one section of the lake can have thin ice.

Usually it takes at least two to three weeks of very cold weather before deep ice is formed on a lake. Here in the northern United States, deep ice doesn’t form until mid­January, at the earliest. Do the tires of cars slip when they drive across ice? Yes, sometimes they do. But almost every car and truck that drives on ice has snow tires, which creates extra friction between the tires and the ice. Some people also choose to put chains on their tires, which gives the tires an even stronger grip against the ice.

In recent years， a number of China's technological innovations have been making their way in the world． Among them， four stand out and acquire a reputation as China's "four new great inventions" of modern times， namely High Speed Railway， Alipay， shared bicycles ， and e﹣commerce．

High Speed Railway   is a type of rail transport that operates significantly faster than traditional rail traffic， "High speed rail travel" has been called the most revolutionary means of transport of the late 20th century and early 21st century． Today， China's high﹣speed railway or CRH， is the best example of such "revolutionary means of transport"． In fact， CRH only began to develop in early 2004， when China issued its "Mid and Long﹣term Railway Network Plan"， the first such development in China's history． It was in little more than six years that China's railway realized its leap﹣forward， which made it possible for China to head into "an era of high﹣speed railway"．

As the American publication "Newsweek" put it： China is now engaged in a "railway revolution"． These 350 kilometer per hour high﹣speed railway trains have made the country's vast territory "substantially smaller"， and changed the country economically．