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    For many years, scientists have said that the earth is getting warmer. Now they have found something new—hot cities! In the southern US, they have found that cities become very hot in summer. For example, the city of Atlanta in Georgia has roof(屋顶) temperature of up to 50^oC while it is 27℃ in the streets! At night, the outside of buildings stays so hot that the heat of the city causes storms over the city!

    China also has the same kind of problems. Every year more farmland is used for factories or offices. More housing is needed, too. As people become richer, they buy more cars. New roads are needed and new car parks are built in the city centers. This all makes cities hotter.

    It isn't easy to change the situation. City planners say that we should plant more trees in the middle of cities. Every new street should have trees on both sides, they say. Trees make the temperature lower, so we should have more trees in our parks and squares. We should also paint our roofs white. If we do this, they do not become so hot. Every roof in a hot and sunny country should have solar(太阳的) roof panels. The electricity from these can be used to run the air conditioners (空调)in the buildings.

    People continue to cut down forests around the cities. This makes the problem worse. Cities are growing faster and faster. By the year 2025, four fifths(五分之四) of the population will be living in cities. If we go on like this, there will not be enough farmland to feed everyone in the world.

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    Almost every Chinese person can recite(背诵) the two lines of the famous poem, "Every grain on the plate comes from hard work". But sadly, many of us don't actually get the real meaning of these lines: Don't waste food.

    A CCTV program reported that the food Chinese people throw away every year is enough to feed 200 million people for a year. Do we have too much food? Absolutely not. According to the UN World Food Program, there were 925 million hungry people around the world in 2013, especially in developing countries. Six million children die of hunger every year.

    Chinese people are well-known for being friendly and generous. Many even feel that they lose face if their guests have eaten all the food on the table. Luckily, a number of people have realized the importance of saving food. What should we do in our daily lives to waste less food?

    ⒈ Don't order too much in a restaurant. Only order as much as you want to eat. If you cannot eat all the food you ordered, take the rest of it home.

    ⒉ Don't leave any food in your bowls while having meals.

    ⒊ Keep an eye on what food you have at home. Don't buy too much, especially for vegetables and fruit.

①Have you ever experienced a quiet carriage(车厢) while traveling by high- speed train in China? According to China State Railway Group, some high- speed trainlines, including the Beijing- Shanghai, Beijing- Guangzhou, and Chengdu- Chongqing lines, have introduced quiet carriage services. The service is popular among travelers and has become a hot topic on Weibo.

②  Passengersareabletochoosequietcarriageswhenbookingtrainticketson12306.  cn—the official train ticket booking system website. On the 12306 App, trains with quiet carriages will have a Chinese character"静" to remind passengers. If you want to buy a second- class ticket with quiet carriages, you can choose" Please first allocate(分配) a quiet carriage seat for me."

③Upon booking, a friendly reminder will pop up. Passengers in the quiet carriage are expected to follow these agreements, including using headphones when listening to music, turning mobile phones to silent mode, stepping out of the quiet carriage when making or receiving calls, and making sure children remain well- behaved.

④There are clear signs on the doors and walls of the quiet carriages. These remind everyone to keep silent. To further create a quiet environment, the voice announcements(通知) in the quiet carriage are lowered to 30% to 40% of the normal volume(音量).

⑤What's more, the staff on the train remind each passenger of the arrival information one- on- one. They also provide gentle reminders to the passengers, reminding them to keep a quiet environment within the quiet carriage. The meal service staff will also refrain from introducing products and services within the carriages. If passengers want to order food, they can conveniently scan(扫描) the QR code on the armrest of their seat, then the staff will quickly pick up the order and bring the food to them. The train also provides passengers with eye masks and earphones.

Thinking of where to travel next？Check out these popular destinations（目的地） and pick your favourite one. 

New Zealand

New Zealand is beautiful no matter what time of the year you visit it. The best time to visit New Zealand is any time you like. The weather here is fine all year round. New Zealanders speak English And there are also many famous adventure activities and exciting sports for you to choose. 

South Africa

If you ask children what their favorite animal is，lions and giraffes must be on the top ten list. Then ask them if they'd like to see them for real!With beautiful beaches，great weather and all those favorite wild animals，you'll also find South Africa can be well worth visiting. 

Ireland

If you want to escape from the large crowds of Europe but still enjoy amazing food，history，road trips and nature，Ireland is the best place for you. It provides visitors with a very relaxing environment，Warning：you may have to give way to sheep on the road!

Portugal

If you are looking for a cheap destination that has a lot of places of interest and activities，Portugal is the place to go. Portugal was recently named as the best European destination at the World Travel Awards. Portugal is also one of the safest destinations in Europe and is becoming very popular with travelers. The busiest season is from June to September. 

The following is a discussion from Mr. Knowall's BBS. The topic of the discussion is about the ways of students' keeping their private (秘密的) things.