At the end of the 19th century, nearly 40 percent of American cars were electric. In cities with early electric systems, battery-powered cars were     1     popular and reliable choice, compared with their gas-powered competitors.     2     early car batteries were expensive and inefficient. At the same time, new     3     (discover) of oil fields lowered the price of gas, and new advances made gas-powered cars more appealing. That's why gas-powered cars     4     (rule) the roads for the next 55 years. Aside from some special-purpose vehicles, electric cars were nowhere to be found.

However, in the 1980s, the tide began to turn. Studies associating car emissions     5     smog(霾) encouraged governments to reconsider electric vehicles. Many companies were developing increasingly efficient batteries at that time. In 2008, Tesla Motors went further,    6     (attract) the attention of the world with its lithium-ion-powered (锂电的) sport cars,     7     could travel more than 320kms on a single charge. Since then, electric vehicles     8     (improve) in cost, performance, efficiency and availability. They can accelerate     9     (fast) than gas powered sports cars. And though some models still have a high upfront cost, they save their drivers money in the long run.

As governments around the world focus on slowing climate change, electric vehicles are now expected     10     (replace) gas-powered ones altogether. Soon, electric cars will reclaim their place on the road.