根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。

      Secret codes (密码)keep messages private。Banks, companies, and government agencies use secret codes in doing business, especially when information is sent by computer.

     People have used secret codes for thousands of years. {#blank#}1{#/blank#}  Code breaking never lags(落后) far behind code making. The science of creating and reading coded messages is called cryptography.

     There are threemain types of cryptography. {#blank#}2{#/blank#}  For example, the first letters of “My elephant eats too many eels” Spell out the hidden message “Meet me.”

{#blank#}3{#/blank#} You might represent each letter with a number, For example, Let's number the letters of the alphabet, in order, from 1 to 26. If we substitute a number for each letter, the message “Meet me” would read “13 5 20 13 5.”

     A code uses symbols to replace words, phrases, or sentences. To read the message of a real code, you must have a code book. {#blank#}4{#/blank#} For example “bridge“ might stand for “meet” and “out” might stand for “me.” The message “bridge out” would actually mean “Meet me.” {#blank#}5{#/blank#}  However, it is also hard to keep a code book secret for long. So codes must be changed frequently.

A. It is very hard to break a code without the code book.
B. In any language, some letters are used more than others.
C. Only people who know the keyword can read the message.
D. As long as there have been codes, people have tried to break them.
E. You can hide a message by having the first letters of each word spell it out.
F. With a code book, you might write down words that would stand for other words.
G. Another way to hide a message is to use symbols to stand for specific letters of the alphabet.

Having learned much about the War of Resistance against Japan, Mao Jingxin didn't like the Japanese when she was a child. “I thought they were cruel and rude,” said the 18-year-old girl from Hebei Province.

But she began to change her mind after she met some Japanese teenagers in a history museum six years ago. These fashionable high school students looked seriously at the history displays and talked to Mao in a friendly way. “I found that they are not bad as I thought,” she said.

Like Mao, many Chinese teenagers' are caught up in this confusion. A survey by 21st Century Teens shows about 51 per cent of Chinese teenagers say they dislike Japan. But most of them still want to have a Japanese friend. Also, Japan lies third on their list of Asian countries that they want to visit, following Singapore and South Korea.

Teens did a survey just before the 60th anniversary of the victory day of the War of Resistance against Japan, which fell on September 3. The survey aimed to encourage understanding and communication between young Chinese and Japanese. Teens also wanted to understand Chinese teenagers' attitudes towards Japan, and how much they actually know about the country.

    As Teens found, more than 60 per cent of Chinese teenagers learn about Japan through the media or books. Only 16 per cent have ever met a Japanese person.

     “Most of my friends hate Japan for what it did to China during World War II. But people should not live in hatred. I think the best way to figure it out is to have contact with the Japanese people myself,” Zhang Yuyua n, a Senior 2 girl, told us in the survey.

“Japan has done wrong to Asian countries including China and it has caused pain to everyone,” said Hikaru, a 17-year-old girl in Kawasaki (川崎市). Having visited China four times and learned much, she understands the importance of communication between the two peoples. She plans to join in an exchange programme with Chinese youth. “Welcome to Japan, my Chinese friends!” She says it with a smile.

    Most visitors come to the UK expecting the rain and weather for which the country is famous. However, when summer finally arrives, British people like nothing more than heading for the coast. Here are some of more famous places of interest that you could expect to visit on a trip to Britain. Black pool, in the northwest of England, is the most visited place in the UK. Each year around 6.5 to 7 million people come to enjoy the miles of sandy beaches, the 158m Black pool Tower and the 11km-long Golden Mile, where there are entertainments, pubs, ice rinks (溜冰场) and even a zoo. On the south coast of the country you can find Brighton. Until 1786, Brighton was a sleepy village. Then the future king, George IV, decided to build a house there, and now it has become a large, international centre. Apart from the beaches, Brighton is famous for its pier (码头). There are theatres, entertainments and restaurants there. Brighton is also fantastic for shopping. If you want to travel a little further, why not go to Cornwall in the far southwest of the UK? South Cornwall offers miles of sandy beaches and beautiful scenery. The climate there is warmer than the rest of Britain, and you can even find palm trees. For a bit more excitement, go to North Cornwall. The scenery there is nicer, and the beaches are famous for their powerful waves. As a result, North Cornwall has become the home of British surfing. One word of warning though, if you are using the roads in the UK during holidays, you can expect long traffic jams on the motorways. It might be better to take the train.

    A new study finds almost one third of the world's population is overweight. Since 1980, obesity rates(肥胖率)in children and adults have doubled in 73 countries, making people more worried. And rates are increasing in many other countries. Obesity is increasing faster in children than adults in many nations, including Algeria, Turkey and Jordan, the report said. But the world's weight problem is growing in both rich and poor countries alike. Researchers say an increasing number of people are dying of related health problems in what they called a "disturbing global public health problem."

    Researchers studied health information from 1980 through 2015. They examined obesity rates, average weight gain in 195 countries. They found that obesity rates are three times greater among youth and young adults in countries like China, Brazil and India. Almost 108 million children and more than 600 million adults were found to be overweight. Egypt had the highest number of overweight adults in 2015. Vietnam had the least. In the same year, the United States had the highest number of overweight children, and Bangladesh had the least.

    Yet hunger remains a problem in many areas. The United Nations said that almost 800 million people, including 300 million children, go to bed hungry each night. Experts said poor diets and lack of physical activity are mainly to blame for the rising numbers of overweight people.

    Growing populations have led to rising obesity rates in poor countries. Often, poor people will eat processed(加工的) foods instead of choosing a diet rich in vegetables.

    The London-based Overseas Development Institute studied the price of food in five countries: Britain, Brazil, China, Mexico and South Korea. It found that the cost of processed foods like ice cream and hamburgers has fallen since 1990. But the cost of fresh fruits and vegetables has gone up.

    Let's look at the movies we can't wait to watch in 2019

    Dumbo (March 29)

    Dumbo is a 1941 American film produced by Walt Disney Productions. The main character is an elephant who is nicknamed “Dumbo”. Dumbo is always laughed at for his big ears, and he is rejected by the other elephants. With no parent to care for him, he is alone. But in fact, he is capable of flying by using his ears as wings. A live-action adaptation of the film directed by Tim Burton is scheduled to be released on March 29, 2019.

    Shazam! (April 5)

    Shazam is an upcoming American superhero film based on the DC Comics character of the same name. Directed by David F. Sandberg, the film is set to star Asher Angel as Billy Batson, a teenage boy who can transform via the magic word “Shazam” into an adult superhero, played by Zachary Levi. It will be the first film version of the character since the 1941 series Adventures of Captain Marvel (the character's original name).

    Aladdin (May 24)

    Aladdin is a fictional character and the role of the film Aladdin (1992) based on Aladdin, a folk tale of Middle Eastern origin He is voiced by Scott Weinger, while his singing voice is provided by Brad Kane. Aladdin never received a formal education, and has only learned by living on the streets of Agrabah. He has to steal food in the local market in order to survive. Mena Massoud is set to play a live-action version of the character in a live action adaptation of the 1992 film.

    Godzilla, King of the Monsters (May 31)

    Godzilla, King of the Monsters is a 1956 Japanese-American science fiction film, co-directed by Terry O. Morse and Ishiro Honda. It is a heavily re-edited American adaptation. For this new version of Godzilla, some of the original Japanese dialogue was translated into English, and some of the political, social and anti-nuclear themes were removed completely.

    A new discovery may change how scientists think about prehistoric humans. Human history is more of a war movie than a romantic comedy, at least as far as other animals are concerned; we may be causing one of the planet's great extinction events at the moment. But a recent discovery means humans might not be as destructive as we thought.

    Large animals have a history of disappearing when humans move to their areas. Scientists have long believed that humans simply hunted big animals because people are really good at hunting. For example, scientists thought humans arrived in Madagascar around 4,000 years ago, but only two thousand years later, giant lemurs, giant tortoises and elephant birds disappeared from the island. Many scientists thought humans had something to do with that rapid drop in biodiversity(生物多样性).

    At least, that's what scientists thought until a group of researchers dug up a lot of bones in Madagascar recently. These bones belonged to the elephant bird, a kind of extinct bird that weighed up to 1,000 pounds. The huge bones were covered in cuts that clearly came from a human hunter. The researchers found that the humans had killed the birds 10,000 years ago...Thousands of years before scientists believed humans had come to the island.

    "Our research provides evidence of human activity in Madagascar more than 6,000 years earlier than suspected, which shows that a different extinction theory is required to understand the huge biodiversity loss that has happened on the island." explained James Hansford, one of the researchers. "Humans seem to have coexisted with elephant birds and other now-extinct species for over 8,000 years, clearly with limited negative influence on biodiversity for most of this period."

    If humans lived among large animals for thousands of years without wiping them out, then maybe our species can't wipe other species out. Rather, extinction is more of a habit we've learned. Perhaps we can unlearn it too.