Electric car sales around the world rose by 54 percent in 2017, taking global stock across the three-million threshold （门槛）, the International Energy Agency （IEA） said in a report on Wednesday. In China, the world’s biggest market for electric vehicles, sales also grew by about half — but their market share remained small at 2.2 percent. In Norway, electric vehicles have by far the world’s highest market share, with 39.2 percent, according to the IEA.

“Supportive policies and cost reductions are likely to lead to significant growth in the market uptake of electric vehicles in the outlook period to 2030,” the report said, If policymakers honor their current commitments to the environment, “the number of electric light-duty vehicles on the road would reach 125 million by 2030,” it added. And if policy ambitions develop further, that number could become as high as 220 million by 2030, it said. But the IEA said that in order for the cars of the future to overtake their petrol and diesel-powered （柴油动力）competitors, governments will have to take the lead.

“The main markets by numbers （China） and sales share （Norway） have the strongest policy push,” the IEA said. “Looking ahead, the strongest current policy signals come from electric car policies in China and California, as well as the European Union’s recent proposal on CO2 emissions （排放）standards for 2030. ”

The EU has committed to cutting 40 percent of its greenhouse gas emissions from 1990 levels, and to improving its use of renewable energy by at least 27 percent. France, home to Europe’s second-biggest car industry after Germany, has gone further by announcing a plan to end sales of petrol and diesel vehicles by 2040, as part of an ambitious plan to meet its targets under the Paris climate accord （条约）. Electric vehicles use batteries instead of petrol or diesel fuel, thereby massively reducing their damage to the environment. But they are not without controversy （争论）.

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．

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.