【推荐3】Why is the world’s population growing?     1    . The reason for the explosion is not that people have been reproducing like rabbits, but that people have stopped dropping dead like flies. In 1900, people died at the average age of 30. By 2000 the average age was 65. But while increasing health was a typical feature of the 20th century, declining birth rate could be a defining one of the twenty-first century.

Statistics show that the average number of births per woman has fallen from 4.9 in the early 1960s to 2.5 nowadays. Furthermore, around 50% of the world’s population live in regions where the figure is now below the replacement level (i.e. 2.1 births per woman) and almost all developed nations are experiencing sub-replacement birth rate.     2    , but you’d be wrong. Declining birth rate is a major problem in many developing regions too, which might cause catastrophic global shortages of work force within a few decades.

    3    What does it imply? First, China needs to undergo rapid economic development before a population decline hits the country. Second, if other factors such as technology remain constant, economic growth and material expectations will fall well below recent standards and this could invite trouble.

Russia is another country with population problems that could break its economic promise. Since 1992 the number of people dying has been bigger than that of those being born by a massive 50%. Indeed official figures suggest the country has shrunk by 5% since 1993 and people in Russia live a shorter life now than those in 1961.     4    Nobody is quite sure, but poor diet and above all long-time alcoholism have much to do with it. If current trends don’t bend, Russia’s population will be about the size of Yemen’s by the year 2050.

    5    As for the USA, it is almost unique among developed nations in having a population that is expected to grow by 20% from 2010—2030. Moreover, the USA has a track record of successfully accepting immigrants. As a result it’s likely to see a rise in the size of its working-age population and to witness strong economic growth over the longer term.

【推荐2】Countries around the globe are spending billions of dollars and lots of time on various space missions, whether to Mars or other planets much further away. Some people argue that we should stop wasting time and money exploring space. Instead, we should feed the world’s poor and find immediate solutions to other problems, such as pollution and fatal diseases (致命疾病). However, others feel this is a shallow view which fails to realise how exploring space helps us.

Firstly, exploring space has already made a difference in the fight against world hunger. It has directly resulted in the many satellites that now orbit Earth. A number of the satellites record data on land and weather patterns. Then the data is transmitted (传送) to scientists on Earth. After careful analysis, the scientists can provide useful recommendations and advice for farmers. As a result, space-based science has helped farming in its efforts to grow enough food to feed Earth’s increasing population.

Secondly, space exploration has already promoted technological improvements that benefit us all. High-end products around the world are made to a higher standard now because of advanced technology which was first created to meet the requirements for space exploration. For example, space technologies have helped the research and development of different types of new material. They have also helped companies make better heart monitors and other machines that doctors regularly use. Today, space technologies are widely used in all kinds of industries, and everyday products such as GPS, memory foam pillows (记忆棉枕头), and smartphone cameras are changing our lives.

Finally, sending astronauts into space has helped people to think about the world’s problems and even to find ways to solve them. Seeing pictures of our planet as an island in a black sea made people realise that our planet’s resources are limited. In order to provide for such a rapidly increasing population, scientists are trying to find other planets that could one day be our new home. The greatest attention at present is on Mars because it is closer to Earth. In the future, humans may live on both planets.

In closing, exploring space provides the world with many different benefits. Therefore, it should continue so as to provide new and better solutions to people’s short-term and long-term problems.

【推荐3】Self-driving cars are just around the corner. Such vehicles will make getting from one place to another safer and less stressful. They also could cut down on traffic, reduce pollution and limit accidents. But how should driverless cars handle emergencies (突发情况)? People disagree on the answer. And that might put the brakes on this technology, a new study concludes.

To understand the challenge, imagine a car that suddenly meets some pedestrians in the road. Even with braking, it’s too late to avoid a crash. So the car’s artificial intelligence must decide whether to swerve (急转弯). To save the pedestrians, should the car swerve off the road or swerve into oncoming traffic? What if such options would likely kill the car’s passengers?

Researchers used online surveys to study people’s attitudes about such situations with driverless cars. Survey participants mostly agreed that driverless cars should be designed to protect the most people. That included swerving into walls (or otherwise sacrificing their passengers) to save a larger number of pedestrians. But there is a hitch (困境). Those same surveyed people want to ride in cars that protect passengers at all costs — even if the pedestrians would now end up dying. Jean Bonnefon is a psychologist at the Toulouse School of Economics in France. He and his colleagues reported their findings in Science.

“Autonomous cars can completely change transportation”, says study coauthor Iyad Rahwan. But, he adds, this new technology creates a moral dilemma (道德两难) that could slow its acceptance.

Makers of driverless cars are in a tough spot, Bonnefon’s group warns. Most buyers would want their car to be programmed to protect them in preference to other people. However, regulations might one day instruct that cars must act for the greater good. That would mean saving the most people. But the scientists think rules like this could drive away buyers. If so, all the potential benefits of driverless cars would be lost.

Compromises might be possible, Kurt Gray says. He is a psychologist at the University of North Carolina. He thinks that even if all driverless cars are programmed to protect their passengers in emergencies, traffic accidents will decrease. Those vehicles might be dangerous to pedestrians on rare occasions. But they “won’t speed, won’t drive drunk and won’t text while driving, which would be a win for society.”