阅读与填词solve · gen · cycle

1Ma Lin, fifteen, was taking the train to Chengdu to spend the summer with her aunt. It was her first trip alone. She put her black suitcase on the luggage rack.

2When the train arrived, she took a black suitcase from the rack, certain it was hers. Her aunt was waiting outside the station, and they took a taxi home.

3Lifting it into the taxi, she found it much heavier than before. At home, she opened it. There were no clothes inside, only a small robot wrapped in a towel, a box of tools and a card: “Youth Robot Challenge, Saturday 9 a.m., Hall 3.”

4On the robot was a name tag: Zhou Bo, with a phone number. Her aunt called, and a boy answered. “I've got a suitcase full of a girl's clothes,” he said. “And my robot is in yours! I spent a year designing it.”

5It was already Friday evening. Her aunt wanted to wait until morning, but Ma Lin looked at the card again. “We'll bring it tonight,” she promised. At nine that night, they met Zhou Bo at his hotel. He unwrapped the robot and checked every part before he smiled.

6On Saturday evening, Ma Lin got a photo of the robot with a gold medal. Under it, Zhou Bo wrote: “From the champion: thank you! Next time, I'm buying a red suitcase.”

1The Golden Ring Circus is back! From 1 to 14 August, our big red tent will stand in Central Square. Come and enjoy acrobats, clowns and jugglers from around the world. There are no animal acts in our show.

Ticket prices

2Adults: 150 yuan. Students aged 12–18 with a student card: 100 yuan. Children aged 3–11: 60 yuan. Admission is free for children under 3, but they must sit on an adult's lap. Family ticket (two adults and two children under 18): 360 yuan, afternoon shows only.

Which show is suitable for you?

3Both shows last 90 minutes, with a 15-minute break.

4Afternoon show (2 p.m.): Seats are not numbered, so come early. This show is especially popular with families.

5Evening show (7:30 p.m.): The show ends with a fire act using real flames, so children under 8 are not admitted. Children under 12 must be accompanied by someone aged 16 or over.

Before you come

6No food or drink from outside is permitted in the tent, not even water. Free drinking water is provided inside. Photos are welcome, but please turn off your flash.

7Special offer: groups of 15 or more get 10% off and can book a private area at the side of the ring. Call 8866 1234 to book.

1Look closely at a candle flame. It is shaped like a teardrop, it points upward, and its tip glows yellow. On a spacecraft, however, the same candle produces a very different flame: round and blue, with no yellow tip.

2The difference comes from gravity. On Earth, a flame heats the gas around it. Hot gas is lighter than the cooler air nearby, so it rises, and fresh air flows in from below and the sides to take its place. This flow keeps bringing oxygen to the flame, and it carries tiny bits of soot up to the tip, where they glow yellow. That is why flames generally point upward.

3In space, where everything floats, hot gas does not rise. With no flow of fresh air, oxygen can only spread slowly toward the flame on its own. Dan Dietrich, a NASA scientist, has said this is about 100 times slower than the airflow on Earth. Because oxygen arrives equally from every side, the flame forms a ball that surrounds the wick, and with almost no soot, it burns blue.

4Between 2009 and 2011, NASA carried out more than 200 tests on the International Space Station in its Flame Extinguishment Experiment. In each test, a small drop of fuel was lit, and a round flame formed around it. In some tests, the flame seemed to go out, yet the fuel went on burning with “cool flames”, too faint to be seen. “We observed something that we didn't think could exist,” said Forman Williams, who led the project.

5Flames in space can also burn cooler and with less oxygen than fires on Earth. As a result, the material used to put out a fire on a spacecraft must be more concentrated. Findings like these help engineers design safer spacecraft, and they may also help car makers design engines that burn fuel more cleanly.

1Wen Jing had planned the trip for months. After the gaokao, she and her best friend Su Mei would cycle around Qinghai Lake, a circuit of about 360 kilometres, in four days. She printed the plan on a card: ninety kilometres a day, no more and no less.

2The first day went to plan, with flat roads and a gentle wind. On the second morning, however, a cold wind blew against them, and Su Mei kept stopping. The lake lies about 3,200 metres above sea level, where each breath contains less oxygen, and her head was aching. “Let's rest in the next town,” she said.

3Wen Jing took out the card. “If we stop now, we'll never achieve today's goal.” Su Mei looked at the road for a moment. “Then go on without me,” she said quietly. Wen Jing made her decision and rode off.

4For two hours she rode hard. Then the sky turned dark, rain began to fall, and her back tyre went flat. She had a spare tube, but the tools were in Su Mei's bag. Her phone had no signal. She stood beside the empty road, wet and shaking.

5Forty minutes later, two bicycles appeared through the rain. One was Su Mei's. The other belonged to an old man from Lanzhou who was riding the circuit alone. He had found Su Mei resting by the road, given her some bottled oxygen and ridden on with her. Ten minutes later, Wen Jing's tyre was fixed.

6For the rest of the trip, Wen Jing rode alongside her friend, at her friend's speed. They finished on the fifth evening, a day late, and the hostel owner gave each of them a certificate. Wen Jing keeps hers with the old card behind it. Next to “Day 2”, she has crossed out “90 km” and written two words: “Stay together.”

1Cliff swallows build their mud nests on the sides of cliffs. In southwestern Nebraska, however, many of them now nest under highway bridges and in concrete culverts beneath roads. These sites suit the birds well, but they come with a new danger: traffic. A swallow resting on the road or flying low across it may have only a moment to escape a car.

2The biologists Charles Brown and Mary Bomberger Brown began studying these birds in 1982, based at a field station in Keith County. Every summer they drove the roads between colonies and picked up every swallow killed by a car. Over the next three decades, the number of such birds decreased. In 2012 they found only four.

3The obvious explanation was that there were fewer swallows to be hit. In fact, the opposite was true: the number of birds nesting near roads increased over the same period. The researchers also found no drop in traffic and no rise in the number of animals carrying off the bodies before they arrived. Younger, less experienced birds, too, turned out to be no more likely to be hit than older ones.

4The answer seemed to lie in the birds' wings. To find out what a typical swallow looked like, the Browns measured birds that had died by accident in their research nets. Compared with these, the birds killed by cars had longer wings. Meanwhile, the wings of the general population became shorter over the years. Shorter, rounder wings allow a bird to take off more steeply and turn more quickly, which may help it escape an oncoming car. Birds with longer wings were more likely to be killed, and so less likely to pass on their genes to the next generation.

5The Browns are careful not to claim too much. In 1996, several days of cold, wet weather kept the swallows from feeding, and about half of them starved. The survivors tended to have shorter wings, so the weather may have played a part too. The birds may also have learned to avoid cars by watching one another. Even so, for many biologists the significance of the study is clear: it offers a rare chance to watch evolution at work within a few decades, driven by something people built.

1When my daughter turned fourteen, a friend told me about an app that would let me read her messages, see every website she visited and follow her phone on a map. “You'll sleep better,” my friend said. I downloaded it that afternoon, looked through everything it could do, and deleted it the same evening.

2I understand why parents are tempted. The online world does contain real dangers, and for many of us a child's safety is of supreme importance. A parent who monitors everything can at least feel in control. But feeling in control is not the same as knowing your child.

3Consider a well-known study from Sweden. Margaret Kerr and Håkan Stattin surveyed 1,186 fourteen-year-olds and their parents. Teenagers whose parents knew a lot about their lives were generally doing well. But that link had more to do with what the teenagers chose to tell their parents than with the parents' efforts to check up on them. And teenagers who felt controlled tended to be doing worse, not better.

4The most useful information a parent has, in other words, is something the child decides to give. Secret monitoring puts that at risk. A girl who finds out that her messages have been read does not usually become more open; she learns to hide things better. Besides, privacy is how young people practise making their own decisions.

5Some readers will say that privacy is a privilege teenagers must earn. Leave aside, for now, whether that is fair. Even as a privilege, it is an unusual one: nobody learns to be trusted without first being trusted a little.

6None of this means absolute freedom. Under certain circumstances, such as clear signs of serious danger, a parent must step in. But my daughter and I have reached a compromise. I don't read her messages or track her phone; she tells me where she is going and calls if her plans change. We have both broken the deal at times, I admit. Yet when something went badly wrong at school last spring, she told me that same evening. No app could have given me that.