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So far, the use of underwater cameras has been limited. Some must be stuck to power wires. Others rely on batteries, which don't tend to last long. Such limits have kept scientists from exploring most of the ocean world. But now researchers have found a way around these problems — underwater cameras can get a new power source from sound.

The camera has two sensors on the bottom. Each is made of multiple layers of a piezoelectric material. When sound travels through the water, it creates waves of pressure, which cause the material to vibrate (振动). And the material changes these vibrations into electrical energy and stores it in a capacitor. Once the capacitor has enough energy, it turns on the camera and takes a picture. Then, it lets the second sensor tap into more sound energy to send the picture. In this way, the sensors not only power the camera, but broadcast the data carrying its images.

Any sound can power it — from swimming fish to a passing ship. One of the sensors can focus on collecting energy for the camera while the other focuses on communication. How quickly the system takes to recharge depends on how loud and close the sound is. In a quiet setting, the camera will take about 10 to 12 seconds. With improved sensors, the camera will charge in less than a second by using sounds from more than 100 meters away.

To record an image, the camera flashes a series of red, blue and green lights. The system then combines what it sees into a single color photo. To communicate, the camera has an internal switch, which controls whether a sensor uses incoming sound for broadcasting. That switch is like a mirror being moved into and out of position. When that switch is in position, the system will use some sound to carry the photo's digital data to a receiver. That receiver picks up the camera's broadcast and assembles the data into an image. And then the undersea photo shoot is done.

Lonely retired people can now buy "grandkids-on-demand" at the press of a button. Using a new app named Papa, the elderly can call on young people to come and visit them and keep them company.

Elderly people, who may have lost touch with their own family, can also ask their rented grandchildren to do chores and drive them around. Papa, which is based in Miami, Florida, is available as a mobile app and a customer telephone line for those without access to a smartphone.

Papa's representatives will then provide a free consultation with the person to see how it can pair college students with them. The app costs the elderly citizens $15 an hour and the Papa Pals receive at least $10 per visit. And the exact sum is calculated by an algorithm (算法) and varies based on the type of trip undertaken by the Papa Pal.

According to Andrew Parker the founder and chief executive of the companionship service, most Papa Pals make on average between $20 to $30 per visit. The average visit lasts around three hours.

Although designed originally for helping old people, Mr Parker believes it could also provide services to other weak groups. The entrepreneur has also targeted babysitting and caring for adults or children with autism as potential future expansion projects within the app. Papa also provides somewhat of a digital education, assisting the elderly set up Netflix or video chat with their grandchildren.

We've rounded four of the most highly expected book releases of November all available now to purchase or preorder on Amazon.

	"Ready Player Two: A Novel" by Ernest Cline (available November 24, starting at $14.99; amazon.com) Ready for a little escapism in the time of Covid-19? Dive into Cline's sequel (续集) "Ready Player One" (which was adapted by Steven Spielberg into a hit movie) to take a thrill ride of a science-fiction adventure through a virtual universe packed with mysteries.
	"Moonflower Murders" by Anthony Horowitz (starting at $14.99; amazon.com) Fans will stay up late reading this suspenseful spin on British crime fiction. In this tale, Ryeland, who has moved to a Greek island to run a hotel, gets caught up in the disappearance of a visiting couple's daughter. Keep the tea kettle handy — this one will be hard to put down.
	"The Best of Me" by David Sedaris (starting at $15.99; amazon.com) When you want a good old-fashioned laugh, turn to this new collection of Sedaris' funniest and most heartwarming essays and fictional stories written over the last 25-plus years.
	"Fortune and Glory: A Stephanie Plum Novel" by Janet Evanovich (starting at $14.99; amazon.com) Fans won't want to miss its 27th installment, taking heroine Stephanie Plum on a dangerous treasure hunt. The story introduces the character of Plum's new enemy, Gabriela Rose. Pace yourself: With this novel, you're in for a wild ride.

注意：1. 文章必须包括表中的全部内容； 
2. 词数为 80 左右。 

参考词汇：网络朋友 online friend(s) ，上当受骗 to be cheated 

Fifty years ago, China successfully launched its first satellite, Dongfanghong 1, and started new chapter in space exploration. ( mark ) its 50th anniversary, the China National Space Administration announced the name for the country's Mars planetary exploration program on April 24.

The mission, Tianwen got its name from a long poem Tianwen  ( write ) by Qu Yuan, a famous poet of the Warring States Period. In the poem, Qu raised a series of questions( concern ) the sky, stars, natural phenomena, myths and the real world, reflecting his doubts on traditional ideas  his pursuit of truth. 

So far, China (make ) remarkable progress in space exploration. In 1970, China launched its first man-made Earth satellite, becoming the fifth country in the world to launch man-made satellites ( independent ) . Over the past few years, China's missions, including the Shenzhou and Change series were designed to explore outer space, expanded ( mankind ) understanding of Earth and the universe.

This time, the Tianwen series will carry out the first Mars exploration mission, represents a milestone for China's move toward deep space.

With the names deep roots in Chinese traditional culture, Tianwen demonstrates the  (determine) and perseverance of Chinese people to move further into deep space. 

I will never forget the adventure I had last summer. It all started when my friends and I decided to go on a camping trip deep in the forest. We were excited to 1  the wilderness and spend time away from our busy lives. 

As we set up our tents, we noticed a strange sound coming from the trees. 2 , we heard a loud roar and saw a huge bear 3  toward us! We quickly 4  our bags and ran as fast as we could to escape the danger. 

After running for several minutes, we 5  we were lost in the woods. Our phones had no signal, and we had no idea how to get back to our campsite. As night fell, we made a 6  to keep warm and tried to come up with a plan. 

Just when we thought things couldn't get any worse, we heard another sound. This time it was a group of wolves howling in the distance. We knew we had to stay 7 and keep the fire going to 8 them off.

The next morning, we decided to 9  a nearby stream, hoping it would lead us back to 10 . After hours of walking, we 11  a ranger station. The ranger (守林员) was surprised to see us and offered to help us find our way back to our campsite. 

We were so 12  when we finally made it back to our tents. Despite the danger and 13  we faced, we were grateful for the experience and the memories we created together. 

The adventure taught me the importance of being prepared and staying calm in 14  situations. It also 15  me of the beauty and power of nature, which we should always respect and appreciate. 

Daily Habits of Naturally Productive People

When it comes to being more efficient at your job, you know the basics. But research shows a whole new side of productivity you may not have realized. 

Focus on being happier.

 Even if a low mood does not completely disable you from functioning, it can decrease your productivity to make you far less efficient. Also, don't hesitate to seek help. This will not only help you achieve a more stable work-life balance, but a new outlook can also open you up to new opportunities and necessary changes. 

Prioritize fitness.

You know the countless benefits of exercise. Even 30-minute bursts of moderate-to-high physical activity just three to four times a day can go a long way in helping you accomplish your personal and professional goals. If you're really not a fan of the gym, join a group class to keep yourself motivated. 

Pressing pause is important. Studies show that prolonged tasks that require high levels of focus, energy, and attention can cause you to become less productive and focused over time. Take brief mental breaks. When we take 'health breaks' we are much more focused and engaged for our next work, in contrast, when we try to work continually on a project without breaks our quality of work tends to deteriorate. 

Don't try to do everything at once.

People believe the more we can do at once, the better.  In fact, the more we multitask, the less efficient and productive we become. Instead, to increase productivity, focus on one task at a time until it's completed and then give all of your attention to the next task. 

A. Make productivity first. 

B. Take breaks at times. 

C. However, research shows the opposite. 

D. Studies found happier people are more productive. 

E. It improves your mood and increase your brain's productivity. 

F. Have a look at these habits of naturally productive people. 

G. Researches show that daylight exposure improves your levels of activity. 

With the invention of the Internet, humanity is now experiencing an adventure toward technological advancement. Nowadays, technology assists us with everyday tasks such as driving, grocery shopping and even dating. Technology is so closely connected to our lives that it's easy to overlook one important question: When technology really starts to control the world around us, what comes next?

Many experts and workers are scared that automation will take jobs from people who need them and give those jobs to robots. I understand their concern. However, if robots are outperforming us at our jobs, then what do humans have left to offer? We have the emotions and imagination that make us human. A machine might work faster than a person, but that's because humans built the machines that way. That, itself, is an amazing accomplishment of the human imagination. We are talented, passionate creatures, who do not deserve to be trapped in miserable jobs anymore!

By now, I hope you're curious to hear which occupations we should focus on in the future. The obvious answer is jobs in technology and robotics. Tech-related jobs will continue to be in big demand, and people who work in these fields will continue to become more important. We should be grateful to them for doing work to take us higher as a society. Besides, we should also focus on jobs in the arts and entertainment. It may sound crazy, but what could better reflect the creativity of the human mind than the arts? I believe technology has opened up our world, allowing us to share our imaginations with everyone!

So, we must ensure that future generations know that we mean it when we say, "follow your dreams. " Welcome to the 21st century: what a time to be alive! There has never been a better time to be yourself, and I can only see it getting even better from here.