题目内容：

    The auto industry, aviation (航空) giants and lots of new companies are increasingly entering the race toward producing flying cars and air taxis, many of which are said to be fully electric. On the surface, there are so many innovations happening that it’s easy to forget that the world hasn’t even seen a fully autonomous car yet, let alone an electric flying vehicle you can park in your driveway.

In fact, there are several hurdles before people are riding through the air. “They are short on technology, and they are short on regulation.” said Jennings-Bates, vice president of a car company.

Uber and Boeing, both world famous companies, have announced ambitious plans for air taxis. However, the types of vehicles they have in mind would require magical electric batteries that don’t exist yet.

Whether the United States actually needs flying cars remains relatively unclear. Aviation experts say that air vehicles help solve congestion problems in big cities. “Today, we have a lot of traffic congestion on the roadways,” said Laurie Garrow, associate director for the Center for Urban and Regional Air Mobility at Georgia Tech. “Air taxis would provide a solution for that.” Others argue that putting traffic in the skies doesn’t solve very much. “We aren’t going to change the world in terms of traffic with flying cars,” said Jennings-Bates. “At best, it may take the place of traffic in the area, which is arguably less pleasant.”

Some experts say it’s not a question of whether flying cars will take off. Instead, it’s a question of how soon the concepts would be safe enough for humans to occupy. “Everyone is very excited and they’re coming up with very different designs,” Garrow said. “But you have a lengthy certification process that will need to go through to make sure the craft and flights are safe.” She estimates that it’ll be about 20 years before the U.S. sees more than test flights.

1.What can we infer about flying cars from Paragraph 1?

A.They are fully electric. B.They are unavailable yet.

C.They need special driveway. D.They equal autonomous cars.

2.What does the underlined “hurdles” in Paragraph 2 refer to?

A.Ambitious plans. B.Big problems.

C.Electric batteries. D.Current innovations.

3.According to Garrow, what’s the main concern about flying cars?

A.Test flights. B.Design.

C.Production. D.Safety.

4.What does the text mainly talk about?

A.Why we should produce flying cars. B.How hard the race of making flying cars is.

C.How close we are to seeing flying cars. D.What people’s opinions are about flying cars.