【推荐3】The Great Chicago Fire of 1871 was the worst disaster of the 19 th century.

The fire is said to have started one evening in Mrs. O'Leary's bar(牲口棚) on the West Side of Chicago.Several hours after she milked her cow,the cow kicked over an oil lamp,and the fire started. We do not know if the story is true,but we do know that the fire began in a barn on the West Side.

The fire spread quickly because of the wooden buildings,a strong wind,and a dry season. The fire lasted 27 hours and spread to all parts of the city. Other cities sent 25 fire companies to help put out the fire.Federal troops(联邦军队) were also used to help fight the fire and keep order,too.   At last rain put out the fire.

There was a lot of damage. 90,000 people were left homeless, and 18,000 buildings were destroyed. Property damage(财产损失) was almost 200 million dollars. In addition, about 300 people died.

People from allover the world helped Chicago by sending food and clothing. Within a month 4,000 cottages(小屋) with two rooms had been built to house people. In a few years,Chicago was completely rebuilt.

【推荐1】Technology is developing fast these years. Let’s see some of the high-tech helpers during the COVID-19 pandemic.

【推荐3】It’s common to carry things on bikes, trains and even planes. But do you know small drones(无人机) can help carry packages to your home?

For two years, Google has been working hard in their secret research lab. Their latest project is called Project Wing.

Project Wing is Google’s invention of a drone delivery service. It is half plane and half helicopter and is slightly bigger than a seagull. It can deliver(投递) packages to buyers by drone to door.

The first drone test was made on a farm in Warwick, Australia. It sent sweets and dog treats to a farmer. The drone flew to the farm, hovered (盘旋), and dropped the package with a wire. Delivery is here!

The best thing about drone delivery services is that delivery time will be greatly cut down. You’ll be able to order what you like online in the morning. And by noontime, the delivery drone will land your package.

Throughout history, there have been different kinds of inventions that have helped people move things around, said Astro Teller, lead scientist of Google Wing, to CNN. Teller thinks Google drones will be the next big step.

Interestingly, drones are not that young. The US has been using armed drones since 2002. But drones may also get another use. Film companies have asked to use drones to shoot videos from the sky.

Yet Google’s delivery drones won’t be able to fly to buyers any time soon. However, Google has proved that drone delivery is possible. And with Amazon announcing their drone delivery service last year, the further research is going on to make delivery drones safe and suitable for buyers.

【推荐1】People are always trying to live a healthy life. You might have read so much on this topic. The following ideas may sound strange, but they can really help you.

Exercise when you are tired.

After a long and tiring day of study, exercising might not sound like a good idea, but it should. In fact, physical activities can provide you with the missing energy. Research shows that exercising for just 30 minutes can make you feel good!

Write by hand to help the brain be active.

Although writing something using a computer is faster, it is much better to remember the whole thing by writing it down by hand. When you read a handwritten text, naturally it’s easier for your brains to remember the information.

Spare more time for yourself.

By sparing the time for yourself and just being alone for a while, you can have a chance to think and get to know yourself better. And you won’t behave impulsively(冲动地).

Drink hot drinks on a hot day.

What cools more on a hot summer morning, cold water or hot water? The study shows that the hot water does make people feel cooler. When you are drinking something hot, the body will feel the change in temperature and increase the perspiration(流汗), which helps you cool down!

【推荐2】Qingming, literally (字面上) means “clear and bright”. It is one of the 24 seasonal division points in China. After the festival, the temperature rises and rainfall increases. And then farmers begin to grow crops. Qingming Festival falls on April 4 this year.

As a festival, Qingming is believed to have a history of about 2,500 years. The most important tradition of Qingming is to honor ancestors and remember the dead family members. So Qingming is also called Tomb-Sweeping Day. When sweeping the graves, people pray, clean the tombstones and burn offerings, usually paper money, paper clothes, paper houses and now even a paper phone.

Lots of ancient poets expressed their sad feelings with words. One of the most famous poems describing the festival was the poem Qingming by Du Mu of the Tang Dynasty as follows: A drizzling rain falls like tears on the Mourning Day; The mourner’s heart is going to break on his way. “Where can a wine shop be found to drown my sad hours?” A cowherd points to a cot amid apricot flowers.

Some traditions of Qingming have brought such problems as traffic jams and air pollution or even forest fires. As part of a greener Qingming campaign, people have been encouraged to pay respect to their ancestors and dead family members online, or burn less or no paper money to protect the environment.

【推荐3】Everyone knows that exercise is important. We all need to exercise. Doctors say it is good for us. It makes your heart and body strong. Children who often exercise are more alert（灵活）. That means they do better in tests and schoolwork than those who             don’t exercise.

There are many ways to exercise. You can walk, run, swim, skate, or play ball games. Make sure you exercise in the following ways: You have to like what you are doing. Exercise enough—but not too much. It’s best to exercise twice a week. Thirty minutes             each time is enough. Try all kinds of sports until you find one, two or even three sports that feel right for you.

You can exercise at fitness centers. They have a lot of equipment（设备）there. The equipment will help exercise your arms, legs and other parts of your body to make you healthy. Some people buy equipment for their homes. But it’s very expensive.