2 . A fourth color might be added to traffic lights to better realize the potential of self-driving vehicles, as stated in a recent paper by researchers at North Carolina State University in the US.

Autonomous vehicles can do more than just drive-they are able to sense their surroundings and upload information. A shared network gives orders to stop at a crossing based on traffic conditions.

The added white lights would be used to signal to human drivers that autonomous vehicles are managing the upcoming traffic flow intelligently. Drivers don’t have to check the traditional lights if the white one is on. “The white lights will tell human drivers to simply follow the car in front of them,” one of the study authors Ali Hajbabaie told the university’s website.

Simulated (模拟的) models showed that autonomous vehicles were able to improve traffic flow on their own. Introducing the white light also has a positive effect on reducing fuel consumption. The higher the percentage of autonomous vehicles at a crossing, the faster the traffic moves, reducing about 40 to 99 percent of the total delay time.

What kind of infrastructure (基础设施) is needed as self-driving technology thrives? In an interview with China Surveying and Mapping magazine, Liu Jingnan at the Chinese Academy of Engineering shared his answers.

To begin with, the vehicle’s network that collects data about the environment and shares the data with other vehicles needs to be intelligent. High-precision maps are needed for autonomous vehicles to plan routes in detail. They can provide both updated information on traditional maps and real-time changes, such as accidents.

For example, when driving around a curve, the navigation (导航) system in the vehicle needs to calculate the safe speed based on the map’s information. And if the area is foggy, the network has to alarm the other cars to slow down.

Other elements on the road need to be upgraded too. For example, road markings should be precise and readable for machines. Sensors should be built on sidewalks and roads to allow vehicles to predict potentially dangerous situations.

5 . I passed my test when I was 19, and I’ve been behind the wheel for most journeys since. After becoming a ________ eight years ago, I became more dependent on my car, thinking that it meant security for me and my child. I couldn’t ________ a world where I didn’t get around on four wheels, but that all ________ when I tried going car-free.

Earlier this year, I ________ to a challenge posed by the climate charity to see what it would be like without my car for three weeks. I ________ an electric family bike. Straight away, I enjoyed having a break from driving, especially on the ________ run. What was once an unpredictable trip to my daughter’s school often stuck in traffic was now a ________ ride along the canal. And my daughter loved every moment of it, which gave me the ________ to know that we were doing the right thing.

Giving up my car didn’t come without its ________. I work in a grocery, and although there are ________ car parking space, there isn’t enough bike parking space to ________ my bike securely. On balance, the benefits outweighed the disadvantages. I felt myself getting ________ because I was getting exercise during my commute (通勤). I saved a bit of money every week just like other participants in this ________.

I was surprised by how ________ it was to give up the car and get around on my bike. I ________ to think it was my duty as a parent to be a driver. Now it’s my duty to get on my bike whenever I can.

Big, heavy vehicles that can’t climb steep hills, running on two steel rails — we’re all familiar with the concept,    1    we call them railways or railroads. Right? However, here’s one of the most unusual railways    2    break the rules in order to reach the places other trains can’t roll: Chongqing Monorail (单轨), China.

Monorails have been around for more than a century,    3    they’ve never quite fulfilled the futuristic promises of those early    4     (promoter). That said, Chongqing Monorail is an     5    (exception) example where the unique qualities offered by monorails are ideally suited to their environment.

Chongqing in China is home to the longest monorail system on the globe, carrying millions of passengers a year on two high-capacity railway lines    6    (total) 61 miles in length. At just over 34 miles, Line 3 is also the    7    (world) longest single monorail line with an annual ridership of around 250 million. Brought into    8    (operate) between 2005 and 2016, the two lines have 70 stations with a mix of underground and elevated sections.

With extreme differences in altitude, Chongqing’s authorities    9    (force) to seek an alternative to conventional trains when they needed to transform its public transport system and monorail’s ability    10    (negotiate) steep climbs and tight bends made it the ideal solution. Finally, Chongqing Monorail emerged.

Think of travel in Greece, and your mind may wander to images of ferries cruising(巡航)across the Aegean Sea. Taking to the water is essential if you plan to travel between the Greek islands, but there     1     (be) plenty of other ways to enjoy Greece’s amazing landscapes, including planes, trains, buses     2     bicycles.

Cycling in Greece is growing in     3     (popular), best done in spring and fall rather than high summer. Strong leg muscles are     4     must to tackle the mountains, or you can stick to some of the     5     (flat) coast roads than the mountain roads. Some are bicycle-friendly, but others have such steep roads     6     cycling is not recommended.

Overall, cycling infrastructure around Greece leaves something to be desired. Bicycle lanes are rare to nonexistent, and there is a real danger from speeding cars —     7     (drive) by locals and tourists alike.

Bicycles may be carried for free on some ferries, while on others, there may be a fee, or they may not be allowed at all because of a lack of space on board.

You can rent bicycles in most tourist hangouts, but they are not as     8     (wide) available as cars and motorcycles. Prices range     9     €10 to €20 per day,     10     (depend) on the type of bicycle. Always make sure the rental cost includes the use of a helmet.

10 . Since the 1920s, a little-known policy called parking minimums has shaped many Americans’ life. In major cities, this meant that any type of building needed to reserve a certain number of parking spaces to accommodate anyone who might visit.

But as the country attempts to cut carbon emissions (排放), we should rethink what transportation and public space look like, especially in cities. Earlier this month, the city of Austin, Texas, became the latest community to undo parking minimums.

“If we want half of all trips to be in something other than a car, then we can’t, as a city, in my opinion, demand that every home or business have at least one parking space for each resident or customer,” said Zohaib Qadri, the Austin city council member who introduced the measure. Reducing dependency on cars was a huge push for the initiative in Austin. Qadri hopes the measure also will lead to a more sustainable city.

The undoing of this law could pave the way for cities to build denser (密集的) housing, increase public transit options, and reduce their carbon emissions, according to Donald Shoup, an engineer and professor. “It isn’t just the housing crisis and climate change; it’s a traffic jam; it’s local air pollution; it’s the high price of everything—except parking,” said Shoup.

Climate change and air pollution are particularly costly outcomes, with both estimated to cost the US billions of dollars every year. Parking spots, meanwhile, can run in the tens of thousands of dollars to construct, with one estimate putting that figure at almost $30, 000 per spot.

But undoing parking minimums does not mean that all parking will disappear overnight. It means that any off-street parking built will not need to meet any minimum standard.

“Austin is the same city that it was two weeks ago,” said Shoup. “It’s going to take quite a while for that city to really get the benefits of their parking space reforms. And so it just removes a roadblock and a barrier to other reforms.”