相关试卷

Secret code (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.Code breaking never lags (落后) far behind code making. The science of creating and reading coded messages is called cryptography. 

There are three main types of cryptography. For example, the first letters of "My elephant eats too many eels" spell out the hidden message "Meet me."

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 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.For example, "bridge" might stand for "meet" and "out" might stand for "me." The message "Bridge out" would actually mean "Meet me."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.

As we continue to explore farther out into our solar system and beyond, the question of humans living on other planets often comes up. Manned bases on the Moon or Mars for example, have long been a dream of many. There is a natural desire to explore as far as we can go, and also to extend humanity's presence on a permanent or at least semi-permanent basis. In order to do this, however, it is necessary to adapt to different extreme environments. On the Moon for example, a colony must be self-sustaining and protect its inhabitants from the airless, harsh environment outside.

Mars, though, is different. While future bases could adapt to the Martian environment over time there is also the possibility of modifying the surrounding environment instead of just co-existing with it. This is the process of terraforming-adjusting Mars' atmosphere and environment to make it more Earth-like. But the bigger question is, should we?

One of the main issues is whether Mars has any native life or not and if it does, should it be preserved as much as possible? If the answer is yes, then large-scale human settlements on Mars should be completely off-limits. Small colonics might be fine, but living on Mars should not be at the expense of any native habitats, if they exist. If Mars is home to any indigenous life, then terraforming should be a non-issue; it simply should not be done.

What if Mars is lifeless? Even if no life exists there, that untouched and unique alien environment needs to be preserved as it is as much as possible. We've already done too much damage here on our own planet. By studying Mars and other planets and moons in their current natural state, we can learn so much about their history and also learn more about our own world. We should appreciate the differences of other worlds instead of just transforming them to suit our own ambitions.

Max Woosey, an l1-year-old from the United Kingdom, has spent his time during COVID-19 doing something pretty meaningful. He slept in a tent for over 500 nights in a row. And he did this not only because he loves the outdoors but in service to others.

Max's father is a Royal Marine (皇家海军陆战队员), so he has courage and love for outdoor activities in his blood. Max's family was looking after their neighbor, Rick, who was dying of cancer. Before Rick passed away, he gave Max a tent and had him promise to have an adventure.

So, after Rick died, Max had an idea. He decided to raise money for Devon Hospice (救济院) , which cared for Rick in his final days. When the first lockdown happened, Max had realized that much of the hospice's fundraising (筹资) also came to a stop. But outside the hospice, a number of people were waiting for help. So Max set a goal to raise 100 pounds by camping out in his front garden.

On March 29th, 2020, Max started his camping adventure in Rick's tent. As he passed hundreds of days camping out, he attracted national attention from the media and even the Prime Minister, who later paid him a visit. More people have donated to Devon Hospice.

Now, 500 days later, he is still camping! Through storms, rain, high winds and cold, he stuck to it. The lessons his dad taught him from the Royal Marines, to never give up, show kindness, honesty and try hard helped support him in tough times.

In all, Max has raised more than 750 000 pounds for Devon Hospice! This made up for about half of the donations they had lost for the year! Max even organized a huge camp at his school playground to show people what children can achieve if they all work together.

Can you survive an unannounced storm? Although there is expert broadcasting and we are equipped with cellphones, there are still some examples when the violent weather takes us by surprise.

While most Atlantic hurricanes form off the coast of Africa giving plenty of early warning, sudden Caribbean and Gulf of Mexico hurricanes form and move rapidly in less than a day's time, endangering everyone and everything in their path.

There have been oil workers trapped off the coast when sudden storms appeared. Field archaeologists have been stuck in seaside areas without storm warnings. A few decades ago, a Texas National Guard group was trapped on the beach by rain-forced flooding and had to ride out a major hurricane during a training exercise. There've been a few cases where travelers were trapped on an island or in a seaside area and unable to escape in time.

Escaping from the storm-threatened areas is generally a choice for most of us - but not for all. Each year thousands of islanders across the Caribbean face the danger of hurricanes without a public shelter to hide in. Most ride out the storm in their homes.

But there are a few things you can do to prepare yourself for some unexpected emergencies. Being prepared for the unexpected may be your best and only defense. If you're headed outdoors for a few days or weeks, you should always carry a flashlight (手电筒) with extra batteries, a GPS device (装置), and a basic medical box. If you're traveling in your car, remember you may suffer from high winds. You'd better not stay inside to avoid being blown away along with your car. Keeping your head and your courage up is crucial to survival in any type of danger. Let common sense guide you and always be prepared for the worst.

Discover all the great Sydney attractions. You'll find many memorable things to do and fascinating museums to visit in Sydney, Australia.

Australian Museum

The Australian Museum (AM) was founded in 1827 and is well-known as the nation's first museum. The AM has been transformed and visitors can now enjoy transformed spaces and updated facilities. Free general admission includes entry to all permanent exhibitions and Prehistoric Playground, which is open daily on Level 2 and features a variety of activities for children of all ages including a fossil lab and interactive dinosaur design station.

Art Gallery of New South Wales

Explore five levels of art at one of Australia's most popular art museums, located within beautiful parklands overlooking Sydney Harbour, just 10 minutes' walk from the city.

See an extensive collection of Australian art, including one of the largest galleries of aboriginal (土著的) art in the country, alongside Asian treasures and leading local and international contemporary art.

Museum of Contemporary Art Australia - MCA

The Museum of Contemporary Art Australia is Australia's leading museum dedicated to exhibiting, interpreting and collecting contemporary art from across Australia.

Located at Circular Quay, the MCA is housed in the former Maritime Services building, a fine example of late Art Deco architecture.

Australian National Maritime Museum

Located at the waterfront of Darling Harbour, the Maritime Museum is an indoor/outdoor attraction and great entertainment for the whole family. The museum has one of the largest and most diverse in-water fleets (舰队) in the world. The museum hosts six permanent galleries, an ever-changing program of temporary exhibitions, and a 3D cinema, ensuring that there is something for everyone.

It was my brother's idea. Let's get Mom a pet dog for her birthday. It would make her happy. I thought it was a good idea, as Mom had always wanted to own a dog. By the time our conversation ended, I had my task: find our mother a dog.

After a careful search, I finally found an ad for dogs in a local newspaper. A nearby family had a dog who had just given birth to five male puppies（小狗）！ All had had their first vaccines（疫苗），and would be ready to leave their mom in a few weeks.I gave them a call.

The man who answered the phone listened patiently to my story and set a date for us to meet the dogs.

When the day arrived, I got into my brother's car. We pulled up in front of some houses that sat along a narrow street. As we stepped onto the sidewalk，we were greeted by noisy barks（吠叫声）. Four dogs had positioned themselves on the back of a sofa and were watching us through a large window. We climbed onto the porch(门廊) and rang the doorbell.

A tall man with graying hair and a kind smile opened the door. As I reached to shake his hand, I could see the puppies behind him, running to get to us. Each puppy wore a different color string around his neck.

We met the man's wife, who wore a similar friendly smile and welcomed us to her home. We met the puppies' parents and then set about the business of selecting a friend for our mother. There were four puppies and four visitors; the man handed each of us a dog. Three of the puppies looked up at us with large, curious eyes. The fourth one, who I was holding, began to wiggle excitedly and kiss my face. "Let's take this one! He's the one! Look how lovely he is!" I said. As far as I was concerned, it was a done deal.

注意：1. 续写词数应为 150 词左右；2. 请按如下格式在答题卡的相应位置作答。 

参考词汇：经典作品 classic 

注意：1. 写作词数应为 80 左右；2. 请按如下格式在答题卡的相应位置作答。 

Dear Tom, 

……

Yours, 

Li Hua