3 . Traffic lights are red, yellow and green. They are very important signals (信号). Traffic lights are usually placed at busy street corners to help control traffic. Sometimes, they are on streets near schools and shops, too. Most young children are taught what each of the colored lights means, so everybody can stay safe.

The first traffic signals were used for trains. The signals were put alongside railway tracks (轨道). The color red was used to mean “stop” because it warned people of danger. A red light was also the easiest color to see from a distance. Train drivers could see the red “stop” light ahead and had enough time to slow down and stop their trains. A green light was used to mean “take care” and a white light meant “go”.

However, there were many dangerous accidents on the train tracks. Some train drivers thought a star shining in the night sky was a white light that meant “go”. So the signals were swapped. The “go” light was changed to green and the “take care” light was changed to white.

During these times, people travelled by train or in carts pulled by horses. Years later, when cars were built, people began to drive them because they could travel much faster than horses. However, the road rules for drivers were not very clear and many people were hurt crossing the roads. Yellow warning signs had to be placed beside the roads to remind drivers to take care and allow people to cross safely.

Today, towns and cities all over the world have traffic lights. Red and green lights match the signals used on the railways. Yellow lights are easy to see, so they are used to warn drivers that they should slow down and prepare to stop.

1. Why was the color red used to mean “stop”?

A．It gave people a warning of danger.

B．It was the first color people thought of.

C．It reminded people of traffic rules.

D．It helped trains run smoothly.

2. What does the underlined word “swapped” in Paragraph 3 mean?

A．Designed.

B．Suggested.

C．Compared.

D．Exchanged.

3. In which order did the “take care” light develop?
a. A white light.            b. A green light.          c. A yellow light.

A．a—b—c	B．b—c—a
C．b—a—c	D．a—c—b

4. What is the passage mainly about?

A．The importance of traffic lights.	B．The meanings of traffic lights.
C．The advantages of traffic lights.	D．The history of traffic lights.

7 . A report lasting almost three decades showed that transportation—flying, driving, rail, commercial shipping, etc.—is responsible for a larger share of domestic greenhouse gas (GHG) emissions (排放) than any other economic sector. Though passenger cars currently account for the largest portion of transportation-related GHG emissions, air travel is one of the fastest-growing polluters. In 2018, aircraft were responsible for 9% of U.S transportaton sector GHG emissions and 2.4% of total carbon dioxide emissions globally.

The carbon dioxide emitted from one round-trip flight from New York to London totals about 1,259 pounds per passenger, according to ICAO’ s Carbon Emissions Calculator—that’s more than what the average citizen of Kenya (and more than 30 other countries)emits over a full year.

Planes also leave behind those ice trails (痕迹)—called contrail clouds—which are even more polluting than the CO₂ they produce. The word “contrails” is a mix of “condensation” and “trails”. They occur when waste gases mix with low-temperature, high-humidity (湿度) air. Contrails are harmful not just because they block sunlight, but also because they trap heat coming up from the ground, finally creating a warming effect below.

Today, alternative fuels that are similar in chemistry to traditional fossil jet fuel, but made from waste and raw materials instead, are becoming more commonplace. San Francisco International Airport has already started delivering sustainable aviation (航空) fuel through a pipeline; American, JetBlue, and Alaska Airlines are some of the industry players that have committed to using it.

New research suggests that because contrail louds form only in very low temperatures, reducing the altitude of fights even slightly could dramatically minimize contrail climate forcing. One study found that just 2% of flights in Japan’s airspace were responsible for 80% of that space’s radiative forcing. The same study estimated that if even 1.7% of flights reduced their altitude by 2,000 feet—which is a normal amount of variation from the flight path anyway—the climate impact of contrails could be cut by 59%.

1. What can we learn about air travel in America from paragraph 1?

A．It emitted more CO2 than passenger cars did in 2018.

B．It is the most convenient means of transportation.

C．It accounted for over two percent of global CO2 emissions in 2018

D．It is considered as the largest air polluter recently.

2. What harm will the contrails of the plane cause?

A．Global warming	B．Low temperatures.
C．Expensive flying costs.	D．Increasing water in the air.

3. Why does the author mention the airlines in paragraph 4?

A．To show alternative fuels are much cheaper.

B．To prove alternative fuels are increasingly popular.

C．To announce alternative fuels have a huge effect on the air.

D．To stress raw materials of alternative fuels are common.

4. What does the new research expect airplanes to do to reduce the harm of the contrails?

A．Change their flight paths.	B．Reduce some flight distance.
C．Develop alternative fuels.	D．Fly at a slightly lower altitude.

8 . Hi Hongbo,

I’m so glad to read about the changes talking place in your city. It’s really good news that you can travel by subway in Xi’an, though there’s only one line there. Here in London we have twelve lines. By the way, we don’t use the word “subway” here. It’s American English. We call it “the Underground”, instead.

The London Underground is very famous. It’s famous for several reasons. First of all, part of the underground railway today is the oldest in the world, which opened in 1863. Secondly, the London Underground is also the first line to have electric trains, in 1890. Thirdly but not the last, the London Underground is the second largest metro system in the world, after the Shanghai Metro. There are 270 stations in the Underground and it has 402 kilometres of tracks (轨道). What’s more, the city of London itself helps make the transportation system famous! I’ve got a few photos to help you build a clear picture of the Underground in my city. They are together with this mail.

In your email, you also said workers were building more lines. I’m sure your city is developing fast. Maybe you can send me a few photos of your city today. I really want to see the changes taking place there. I’m happy for you to live there in an ancient city with such a new look!

So much for now. I’ll write soon again. Best wishes!

1. Where is the writer from?

A．From Xi’an.

B．From Shanghai.

C．From London.

D．From New York.

2. The second paragraph mainly tells us________.

A．when the first subway was opened in the world

B．when the London Underground first used electric trains

C．why the London Underground is the oldest subway in the world

D．why the London Underground is famous in the world

3. In the email, the words “subway”, “underground”, and “metro” mean________.

A．almost the same thing	B．two different things
C．three different things	D．nothing like each other

4. What does the writer want Hongbo to do?

A．To buy a good book about Xi’an for him.

B．To post him some postcards of Xi’an.

C．To tell him more about Xi’an subway.

D．To send him a few photos of Xi’an.

9 . For the decade between the end of the financial crisis and the coronavirus pandemic, the ride-hailing app Uber boomed. The company’s business model relied on the flexibility of the rapidly-growing gig economy(零工经济), and its sky-high valuation directly represented its dominant market position.     1    .

Now its sufferings illustrate how those trends are shifting again. After almost a decade of being able to rely on cheap and swift Ubers to get around, city residents must get used to a new experience. A shortfall of British drivers got so bad that the chief executive Dara Khosrowshahi met with unions to recruit new workers on a visit to London.

There are some factors accounting for this shortage. During lock-downs few were taking trips, but with the reopening, and the urge to mingle(社交往来)again, came a sudden bounce-back(反弹). Uber said that demand in London had risen by about a fifth in 2021 and even more in smaller UK cities.     2    .

The flexibility and casual working arrangements that once so benefited the company now work in reverse in times of labour shortage.     3    . Uber has been forced to raise charges in London and offers a bonus if drivers can recruit others.

In the past two years, the price of an Uber has increased by 92 percent, according to Rakuten Intelligence. Higher prices are likely to be here to stay.     4    . Perhaps, then, Uber will demonstrate just how abnormal the decade between the end of the financial crisis and the arrival of the pandemic really was. The era of cheap Ubers may be at an end.

A．Workers have little, or no, loyalty to the company and can switch between different apps depending on which offers the better, or closer, ride

B．The government is now racking its brain to figure out ways to help support Uber to get through this difficult time.

C．The prospect of this huge industry cannot be underestimated.

D．In the meantime, thousands of drivers had found other jobs; even while economies were locked down drivers were still needed for takeaway and online shopping deliveries.

E．The question is what happens when more normal circumstances return.

F．It even sparked the word “Uberisation” to describe how its example helped transform industries, jobs and society.