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 three main 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 “135520135.”

    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.

Get a Better Night's Sleep

    You're trying to get a good night's sleep, but why do you still find yourself staring at the ceiling? It's time to listen to what some unexpected experts have to say.

Get the Basic Equipment Right.

    There's really good study on the basic equipment for sleep. {#blank#}1{#/blank#}Firstly, most people prefer a mattress （床垫）that is not too hard and not too soft. Secondly, if your mattress is eight to ten years old, you should get a new one. Seventy-two percent of people said they slept better on their new mattress than they did on their old one.

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    Watching TV at night may seem relaxing. However, it beams light into your eyes, which is a “warning” signal for the brain.{#blank#}3{#/blank#}Besides, the cooler white and blue light from a computer screen encourages brain activity and makes your brain difficult to calm down. Download the software at stereopsis.com /flux. It gradually makes your screen less bright at sunset, turning its colors a warmer red one.

Keep you Cool.

    One of the best signals from the body to go to sleep is a decrease in body temperature. I suggest sleeping in a very cool environment, about 19℃. A hot bath will increase your skin temperature, which finally decreases your main body temperature. {#blank#}4{#/blank#}

Make Sleeping Pets Lie.

    Sometimes your dogs might need the noise of machines. Many dogs are sensitive to noises outside, like other dogs barking or neighbors coming home late. A noisy machine will drown out the noises that are keeping your pet up, which keep your pet from waking you. {#blank#}5{#/blank#} If you keep them awake during the day, they're more likely to sleep at night.

 A. Read a book before bed instead.

 B. Take a bath a half-hour or so before bedtime.

 C. You also learn dogs sleep when they're bored.

 D. The dog is very loyal to his master.

 E. It proved two theories.

 F. You don't need a really beautiful mattress.

 G. Switch off the Box.

Saving money while traveling

    There are a lot of matters to think on before going out on a trip.  If you fail to plan the trip properly, then money will simply let itself loose from your pocket. Moreover, if you haven't planned a road map of your tour,  then confusion is quite inevitable (必然的). {#blank#}1{#/blank#}

    Package tours. Tours and travel agencies have attractive offers for tourists wanting to spend a couple of days on trips. {#blank#}2{#/blank#} Once you have accepted the package tour, all your expenses during the travel will be greatly reduced. You can save a lot in lodging(住宿 ) and traveling.

    Inexpensive lodging. Never choose expensive lodging if your tour is a low-budget one. People tend to spend a lot booking luxury hotels (豪华旅馆),  and save little to enjoy other activities during the trip. This idea is absolutely not wise when spending limited money on the trip is your main aim. Moreover, the expenses increase quickly when your kids are with you. {#blank#}3{#/blank#} You can use the money saved on good food and amusement.

    {#blank#}4{#/blank#} The peak season is the time when rates are sky high due to the increase of millions of tourists who can afford to spend a lot of money. You, not being amongst this crowd that can spend generously, must book your holidays during the off season.

    A guide map. Make a guide map about the places to visit, expenses of travel and the activities to try. While planning you should also estimate (估计) your total expenses. Calculate the maximum amount and try to spend less than that. {#blank#}5{#/blank#} Refer to the guide map while traveling and follow the money-saving travel tips as much as possible.

A. Reduce shopping.

B. Off season travel.

C. You must keep yourself updated with such offers.

D. This will help you to keep actual expenses below the estimated.

E. You can save lots of dollars when you don't have a credit card.

F. Therefore, book a fairly low-price lodge to save a few dollars.

G. So knowing some money-saving travel tips becomes necessary for you. 

    The world is becoming more and more connected, but many people feel lonely in the midst of it. You might not feel lonely right now, but there might be times when you do. Here are some tips on dealing with loneliness:

    Be positive about yourself.{#blank#}1{#/blank#} If you constantly think of yourself as ugly, mean, or unattractive, then it will be difficult for you to connect with others. You must accept yourself before you can accept others. It's common that you might have some negative qualities. So does everyone else. So in order to get rid of loneliness, you should focus on your positive side and think of yourself in a positive way.

    Have an attitude of gratitude (感恩){#blank#}2{#/blank#}It's easy to focus on the negatives in life, but don't forget that there are also many positives. Remember them and be thankful. What does this have to do with loneliness? Well, if you are grateful, then you will become cheerful{#blank#}3{#/blank#} See the positive side of others. Just as you should see the positive side of yourself, you should also see the positive side of others. Everyone has shortcomings, but everyone also has a positive side.{#blank#}4{#/blank#}That will make you like them and make it easier for you to connect with them.

    {#blank#}5{#/blank#} The more you think about yourself, the more likely it is for you to have a pity party and feel lonely. For example, you might think that nobody likes you or cares about you. So it's important that you shift your attention away from yourself. It can be as simple as smiling at your neighbors or holding a door for a stranger.

A. Join a community group.

B. Do something for others.

C. Negative thoughts can kill you.

D. Instead, try to make more friends.

E. And that will attract people to you.

F. Count your blessings and be grateful for them.

G. So choose to value the positive aspects of them.

Five steps to make a difference to the oceans

    The oceans are being seriously polluted now. Plastics are harming the marine (海产的) life. Carbon pollution is warming the oceans and increasing their acidity(酸度). Waters are being overfished. {#blank#}1{#/blank#} Here are some steps we can take to help make a difference.

    ⒈Bring our own bags. {#blank#}2{#/blank#} Try carrying a reusable bag at all times, including while traveling, and bringing our own things to work to avoid relying on plastic items.

    ⒉Talk about it now. We should carry that conversation into public places. Talk to our friends and family about why the ocean is important and why we take steps to help it, and challenge them to do the same.

    ⒊{#blank#}3{#/blank#} A good way to make a difference is to organize a garbage cleanup now. Whether it's an inland cleanup or one near the coast, plan one in our community.

    ⒋Throw away our cars. {#blank#}4{#/blank#} When we hang out, we should reduce our carbon footprint, which may help slow global warming and ocean acidification as well as conserve energy

    ⒌Recycle, obviously. Experts say recycling is an obvious action to take. Check on what can be recycled in our community, and make sure you're separating out your plastic.

    In summary, think about it more and act on it more. The more someone thinks about plastics and plastics pollution, the environment and the consequences of our actions, the more likely they are to act on it. {#blank#}5{#/blank#}

A. Plan a cleanup.

B. Choose public transportation over driving our cars.

C. Driving cars is not a good way to protect the oceans.

D. However, experts say there's still hope to make a difference.

E. However, marine life plays a very important role in the oceans.

F. If everyone can contribute to the oceans, the oceans will be well preserved.

G. Whenever we put something, we should bring our own bag, but not a plastic one.

    The most important thing to keep in mind when deciding to serve another is that service expects no rewards. When you expect something in return, and are not serving out of the goodness of your heart, others will notice. Sure they'll thank you. {#blank#}1{#/blank#}

    When you give from your heart, the real power of service comes into play. Serving is a great opportunity to strengthen your trust and respect for another, and for them to do the same to you. Not only do you feel great about helping out, but you build your relationship with them, and they will feel more willing to help you in the future. {#blank#}2{#/blank#}

    However, why is service so rarely seen these days? {#blank#}3{#/blank#} Sure, living in this day and age does not leave us much time, and the last thing people want to do is more work. I'm too busy, there's too much work, or I don't have the time, "may run through your head when you hear the word service, but the truth is the benefits are worth the sacrifice. Gandhi once said that, "The best way to find yourself is to lose yourself in the service of others." {#blank#}4{#/blank#} Some ideas of places you can serve are volunteer centers, nursing homes, boys and girls clubs, and so on. You can serve people as long as you want to.

    {#blank#}5{#/blank#} Although it does take some work, the benefits are more than worth the sacrifice. Not only do you feel better about making another's day a little less stressful, but you strengthen your relationship with them and they will be more willing to help you in the future.

A. It's a win-win situation.

B. Service is simple.

C. Overall, service and selflessly giving to others is very powerful and has many benefits.

D. And they will offer you worse service.

E. Service is a complex event.

F. The problem is, there's always an excuse not to serve.

G. But the service becomes more of a situation, "I'll do this for you if you do this for me".