When the Normans built their first simple wooden castles in England，they built them on the top of small hills.The first permanent castles were made of stone and built with thick walls.The main building was usually surrounded by walls which overlooked the moat (护城河)．

     The entrance to the castle was usually over a drawbridge (吊桥) leading to the main gatehouse.The drawbridge could be raised or lowered and an iron grille (栅栏) could be lowered to shut off the entrance to the gatehouse.

     As time went on，the castle builders became more advanced in their techniques.Instead of building a strong central building and surrounding it with walls of lesser strength，they thought out the idea of surrounding a central area with huge walls which could contain all the main rooms of the castle.These walls usually had many towers and these towers were really a series of main buildings along the castle walls.In building these castles they used hill sites whenever possible in order to give the castle a better position.Because the outside world was shut off by a barrier or curtain of defences，they are called “curtain wall” castles.

     With the passing of time there was less need to build strong castles and nobles built manor (庄园) houses.These manor houses often had battlements and iron grilles，but they were built more for comfort and included many of the conveniences and luxuries of the large houses which were being built in the towns.

     Unfortunately，many English castles were damaged or destroyed completely during the Civil Wars of the 1600s.

    No student of a foreign language needs to be told that grammar is complex. By changing the order of the words and by adding a range of auxiliary verbs (助动词) and suffixes (后缀), we can turn a statement into a question, state whether an action has taken place or is soon to take place, and perform many other word tricks to convey different meanings. However, the question which many language experts can't understand and explain is—who created grammar?

    Some recent languages evolved due to the Atlantic slave trade. Since the slaves didn't know each other's languages, they developed a make-shift language called a pidgin. Pidgins are strings of words copied from the language of the landowners. They have little in the way of grammar, and speakers need to use too many words to make their meaning understood. Interestingly, however, all it takes for a pidgin to become a complex language is for a group of children to be exposed to it at the time when they learn their mother tongue. Slave children didn't simply copy the strings of words used by their elders. They adapted their words to create an expressive language. In this way complex grammar systems which come from pidgins were invented.

    Further evidence can be seen in studying sign languages for the deaf. Sign languages are not simply a group of gestures; they use the same grammatical machinery that is found in spoken languages. The creation of one such language was documented quite recently in Nicaragua. Previously, although deaf children were taught speech and lip reading in the classrooms, in the playgrounds they began to invent their own sign system, using the gestures they used at home. It was basically a pidgin and there was no consistent grammar. However, a new system was born when children who joined the school later developed a quite different sign language. It was based on the signs of the older children, but it was shorter and easier to understand, and it had a large range of special use of grammar to clarify the meaning. What's more, they all used the signs in the same way. So the original pidgin was greatly improved.

    Most experts believe that many of the languages were pidgins at first. They were initially used in different groups of people without standardization and gradually evolved into a widely accepted system. The English past tense—“ed” ending— may have evolved from the verb “do”. “It ended” may once have been “It end-did”. It seems that children have grammatical machinery in their brains. Their minds can serve to create logical and complex structures, even when there is no grammar present for them to copy.

    Facebook founder Mark Zuckerberg took out full-page ads in British and American newspapers on Sunday to apologize for the Cambridge Analytica scandal（丑闻）, admitting the quiz app built by a university researcher that leaked（泄漏）Facebook data of millions of people was a “betrayal of trust”.

    Since the scandal broke, the public has become more aware and concerned about how their online behavior may be used for purposes to which they have not agreed. It emphasizes the urgent need for better protection of personal information.

    To better protect personal data privacy（隐私）, targeted laws are needed. More effective cooperation should be carried out to protect people's privacy online as soon as possible.

    Countries, such as the United States and China in particular, which are global leaders in the use of big data should accelerate legislation（立法）on how it can be collected and for what purposes it can be used.

    At the same time, a closer watch should be kept on the world's major internet companies, such as Apple, Facebook, Amazon, Google, Microsoft, Alibaba, Tencent and Baidu to ensure they do not acquire unnecessary personal information or misuse the information they obtain. Despite the huge challenge such personal data protection may pose to their established profit-making models, these companies should know that the more powerful they are, the bigger responsibilities they shoulder.

    Strengthened efforts for personal privacy protection do not mean that big data must not be used, but that it is used appropriately. Big data is like a mountain or gold, and overemphasis on its security at the expense of its use will undoubtedly waste a valuable resource. The key problem is how to promote its use while guaranteeing people's privacy to be protected.

    Earthquakes strike suddenly at any time of the day or night, but there's no way to tell when. If an earthquake happens, it may cause many deaths, injuries and damage. So you need a good preparation ahead of time. Decide how and where your family will get together if separated. Choose an out-of-state friend or relative that the family members can call after the quake to report where they are and how they are. Know the safe places in each room: under the strong tables, desks, or against inside walls. Keep enough food, water and other things, including a flashlight, a radio, medicines and clothing.

    During the earthquake, you should keep a clear head and never be too nervous to know what to do. Protect your head and neck with your arms. If possible, take a book, a pillow or any other things to protect yourself from falling glass and ruins. If you are indoors, you must immediately lie under any strong furniture. If outdoors, move to an open area away from trees, buildings, walls or power poles. If you are in a narrow valley, move to the centre of it and look up for falling stones. If you are in a car, move to the side of the road and stop the car. Do not stop near buildings, power lines or on or under bridges. Stay in your car until the shaking stops.

    Do not move a badly injured person unless he is in great danger after the earthquake. Do not use the telephone immediately unless there is a serious injury or fire. Turn on your radio for instructions and news reports. Be prepared for aftershocks. If you want to leave your home, post a message inside your home telling your family members where you can be found.

With advanced communication technologics making the iconic British red telephone boxes expendable (可抛弃的）, a US firm is all set to bring them back to use. Call boxes would be changed into mini-offices for workers on-the-go and will offer free coffee to subscribers (认购者).

Bar Works Inc's chief executive Jonathan Black, a Briton living in New York, said that his company will renew telephone boxes with fully functional printers, scanners, 25-inch screens and Wi-Fi. Bar Works specializes in offering bar-themed work stations in prime locations, charging customers with a monthly subscription in return for free access to the business and office supplies. The company plans to operate in a similar manner, offering British customers with monthly memberships to "Pod Works" for £19.99 ($29).

The company will refit telephone boxes in five major British cities and has already rented and changed 15 old call boxes in London and Edinburgh. As expected, they are coming into use by the public in the coming months. "Given the prime location, above all else, of the telephone boxes, the launch is expected to gain at least 10, 000 members by the end of 2021. It's an alternative to, say, Starbucks but obviously it provides you with total privacy. " said Black.

Thanks to mobile phones, the red telephone boxes have been effectively made expendable. According to a report by the Daily Mail, retired telephone boxes, especially those damaged deliberately, are sent to a "telephone box graveyard" of sorts, where they take great pains to restore to their former glory before being sold to collectors across the globe. Such is the demand for properly restored telephone boxes, that it is not uncommon for them to be sold for amounts as high as £10, 000.

Despite its setback, in a recent survey, the British red telephone box, which was originally designed in 1920, was voted the greatest British design of all time.

Iman, the last Sumatran rhino(犀牛) in Malaysia, died in 2019 — bringing the endangered species one step closer to extinction. Now, Malaysian scientists are hoping to use tissues and cells from Iman and other dead rhinos to bring the population back.

"Before the three rhinos (the last survivors in Malaysia) died, we got their cells, and the cells are still alive — which is why I'm quite confident," Dr. Lokman said. "If we don't have any cells, or have just tissue that isn't living anymore, we wouldn't be able to do anything. But now we have a living thing that we can use. "

The cells came from the rhinos'hearts, lungs and brains. What is the most important is that the team collected stem cells (干细胞). One possible approach is to develop these stem cells into an egg (卵子) and sperm (精子), to create an embryo (胚胎) that will be placed into a surrogate mother (代孕母亲). She will likely be another rhino, either a Sumatran rhino from another country or another species. The other method is to take the egg of a surrogate animal, remove the nucleus (细胞核), and join it with a Sumatran rhino's body cell. This technique was famously used to clone Dolly the sheep in 1996. Dr. Lokman and his colleagues are trying both ways. The team is still in the early stages; next, they need to find a suitable surrogate female.

Sumatran rhinos are listed as critically endangered by the World Wildlife Fund. There are less than 80 alive in Indonesia and Thailand. The fall in the population was first caused by hunting. Later, the situation was worsened by the loss of habitats and human activity. Unfortunately, there are now only five remaining rhino species worldwide, and all are threatened. Some sub-species have already died out; the western black rhino was declared extinct in 2013. And it is a pity that the last male northern white rhino died in 2019.