In France, a man walks on what can only be described as a human-sized hamster wheel. The wheel moves around and around, as the man keeps walking. What is he doing? He is lifting a heavy object to the top of a tower the same way workers moved such objects 800 years ago.

    In the 13th century, workers did not have the 100-meter tall cranes they now use to build tall buildings. So they had to be creative and come up with simple machines to get their work done.

    The man on the large wheel is walking at a reasonable speed. The wheel turns and pulls a rope connected to a pulley(滑轮)at the top of the tower. Another rope tied to the pulley lifts supplies from the ground.

    This is just one way skilled craftsmen arc building a 13th-century castle without using modern tools. Crew have been working on the castle since 1997. It is being built in the Burgundy area of central France. Organizers expect the work to last another 10 to 15 years. That means it will take close to 30 years to finish the project.

    The crew are making progress at about half the speed of the workers from 800 years ago. That is because many of them are accustomed to using modern tools. When the crew use heavy chisels(凿子）and hammers to break rock, as they did hundreds of years ago, they are learning as they go. The goal of the project is to learn more about old building techniques in case they might be of use today.

    Clement Guerard, 44,is a stonemason; he cuts and builds with stone. He has been working on the tower for 17 years. He said one way he is able to work on something like this for so long is by forgetting “some of the pace of modern life", he is able to adapt to working by hand.

    Doing well in high school prepares students for life in college and beyond, so achieving student success is important. High school students learn valuable information from class lectures and homework, and by asking for help when it is needed. Being prepared for tests and engaging in school activities can help a student to achieve success in high school.

    Complete any homework you are assigned on time. Then, if you need help understanding a concept you will have plenty of time to get help.

    Create a study area in your home. This can be a quiet bench outside or a seating area in your room. If you like to listen to music while studying, listen to classical or relaxing music. Be sure to have plenty of lighting in the area to read your textbook or notes.

    Keep a schedule. If you have extra-curricular activities like sports or school meetings, make sure to schedule your homework and study time around them. Keeping a schedule will allow you to get better grades while they are having fun in high school.

    Eat breakfast. Having breakfast each morning before school will give you energy and brain function to pay better attention in class. Eat snacks during study sessions to keep alert and focused on your work.

    Create a study group to help fellow high school students and get help if you need it. Studying with others will help reinforce concepts and information, and if you need help there will always be someone there to help you before you get behind in your studies.

    Set up after-school hours with your teacher if you need extra tutoring. Visiting a teacher for one-on-one time before a test will help you nail down those last few concepts you need help with.

    Imagine a mass of floating waste is two times the size of the state of Texas. Texas has a land area of more than 678,000 square kilometers. So it might be difficult to imagine anything twice as big. All together, this mass of waste flowing in the North Pacific Ocean is known as the Great Pacific Ocean Garbage Patch（太平洋垃圾带）. It weighs about 3,500,000 tons. The waste includes bags, bottles and containers-plastic products of all kinds.

    The eastern part of the Great Pacific Ocean Garbage Patch is about 1,600 kilometers west of California. The western part is west of the Hawaiian Islands and east of Japan. The area has been described as a kind of oceanic desert, with light winds and slow moving water currents（流，流动）. The water moves so slow that garbage from all over the world collects there.

    In recent years, there have been growing concerns about the floating garbage and its effect on sea creatures and human health. Scientists say thousands of animals get trapped in the floating waste, resulting in death or injury. Even more die from a lack of food or water after swallowing pieces of plastic. The trash can also make animals feel full, diminishing their desire to eat or drink.

    The floating garbage also can have harmful effects on people. There is an increased threat of infection（感染）of disease from polluted waste, and from eating fish that swallowed waste. Divers can also get trapped in the plastic.

    Its existence first gained public attention in 1997. That was when racing boat captain and oceanographer Charles Moore and his crew sailed into the garbage while returning from a racing event. Five years earlier, another oceanographer learnt of the trash after a shipment of rubber duckies got lost at sea. Many of those toys are now part of the Great Pacific Ocean Garbage Patch.

    In August,2017, a team from the University of California, San Diego became the latest group to travel to it. They were shocked by the amount of waste they saw. They gathered hundreds of sea creatures and water samples to measure the garbage patch's effect on ocean environment.

    There is a common belief among parents that schools are no longer interested in spelling. No school I have taught in has ever considered spelling unimportant as a basic skill. There are, however, quite different ideas about how to teach it, or how much priority(优先) it must be given over general language development and writing ability. The problem is, how to encourage a child to express himself freely in writing without holding him back with spelling.

    If spelling becomes the only point of his teacher's interest, clearly a bright child will be likely to "play safe". He will write only words within his spelling range(范围). That's why teachers often encourage the early use of dictionaries and pay attention to content rather than technical ability.

    I was once shocked to read on the bottom of a sensitive piece of writing about a personal experience: "This work is terrible! There are far too many spelling mistakes." It may have been a sharp criticism(批评) of the pupils technical abilities in writing, but it was also a sad thing for the teacher who had omitted to read the composition, which contained some beautiful expressions of the child's deep feelings. The teacher was not wrong to draw attention to the mistakes, but if his priority had centered on the child's ideas, an expression of his disappointment with the presentation would have given the pupil more hope to seek improvement.

    Humans and many other mammals have unusually efficient internal temperature regulating systems that automatically maintain stable core body temperatures in cold winters and warm summers. In addition, people have developed cultural patterns and technologies that help them adjust to extremes of temperature and humidity (湿度).

In very cold climates, there is a constant danger of developing hypothermia, which is a life-threatening drop in core body temperature to below normal levels. The normal temperature for humans is about 37.0℃. However, differences in persons and even the time of day can cause it to be as much as 6℃ higher or lower in healthy individuals. It is also normal for core body temperature to be lower in elderly people. Hypothermia begins to occur when the core body temperature drops to 34.4℃. Below 29.4℃, the body cools more rapidly because its natural temperature regulating system usually fails. The rapid decline in core body temperature is likely to result in death. However, there have been rare cases in which people have been saved after their temperatures had dropped to 13.9-15.6℃. This happened in 1999 to a Swedish woman who was trapped under an ice sheet in freezing water for 80 minutes. She was found unconscious, not breathing, and her heart had stopped beating, yet she was eventually saved despite the fact that her temperature had dropped to 13.7℃.

In extremely hot climates or as a result of uncontrollable infections, core body temperatures can rise to equally dangerous levels. This is hyperthermia. Life-threatening hyperthermia typically starts in humans when their temperatures rise to 40.6-41.7℃. Only a few days at this extraordinarily high temperature level is likely to result in the worsening of internal organs and death.

When driving, Clara - Marina Martinez makes a note of any unusual behaviour she sees on the road. She then feeds these into machine- learning algorithms(算法), a form of AI, which she is helping develop for Porsche Engineering.

Those algorithms are intended to produce a system reliable enough for a car to drive itself. Such a fully autonomous car, known in the industry as Level 5, should be able to complete an ____ entire journey without any intervention (介入) from the driver, and deal with all situations on the road. But this is proving hard to achieve, and many attempts to do so are being abundoned. Last year, for instance, Uber sold off its unit developing self- driving cars.

Autonomous vehicles are said to be not just convenient but potentially safer. However, just as people take time to learn how to drive safely, so do machines. And machines are not quick learners. The RAND Corporation calculates that to develop a system 20% safer than a human driver, 100 self- driving cars would have to operate 24 hours a day, 365 days a year.

 Carmakers such as Porsche therefore speed up the development process using simulators(模拟器). These teach software about dangers rarely encountered in reality. Dr Martinez and her colleagues employ "game engines" to do this. These are used to create virtual worlds through which the software can drive. Objects in these virtual worlds are assigned their physical characteristics ( ie, buildings are hard, people are soft) so that the sensors in vehicles respond in the appropriate way. Once the software has been trained, it is tested in real autonomous vehicles by re- creating those situations on a test track.

 How quickly all this will translate into reality remains to be seen. Both regulators and customers will need to overcome the doubt that a software driver really can be safer than a human being.

 From Porsche's point of view, though, there is another question. Given that much of the reason owning a sports car is for owners to show off their driving skills, just how big a market will there be for a version where software takes those bragging(炫耀的) rights away?