2 . Bookstores are fascinating places. That’s because the books on the shelves can take you away to magical lands, help you learn a foreign language, or cook a delicious meal. But when your community is too small to house a real brick bookstore, sometimes you have to make a compromise. A mobile bookstore that brings books around the country was the result. That is the case for Rita Collins, 70, who dreamed of opening a used bookstore after retiring from teaching.

A business planning class from the American Booksellers Association convinced Collins to abandon her idea that opening a bookstore in the small town where she lives, which would not be sustainable. Eureka, Montana, located just seven miles from the Canadian border, only has a population of 1,517. Collins asked her instructors about a traveling bookstore on wheels and they were skeptical. But she persevered.

Collins was inspired by Dylans Mobile Bookstore, a traveling bookstore in Wales run by Jeff Towns. She contacted Jeff for advice but she was largely on her own when it came to building her bookstore. First, she had to find a vehicle large enough to stand in. Then she had to have it refitted with shelves that would hold the books at a 15-degree angle so that they would stay in place while in transit. Collins named her bookstore St Rita’s Traveling Bookstore, which has been on the road since 2015.

At first, she drove through Montana and then she made her first cross-country trip in 2016. After she retired in 2017, it became a full-time job all year round. Collins and her mobile bookstore have visited 30 states, stopping at festivals and events along the way. While the locations change, some things always stay the same. Collins loves meeting people and making connections. While she loves what she does, Collins doesn’t think she can keep doing it. In several years, she hopes to pass her traveling bookstore onto another bibliophile who shares the same interest and will keep it on the road.

4 . It’s common knowledge that the woman in Leonardo da Vinci’s most famous painting seems to look back at viewers, following them with her eyes no matter where they are in the room. But this common knowledge turns out wrong.

A new study finds that the woman in the painting is actually looking out at an angle of 15.4° off to the viewer’s right — well outside the range that people normally believe when they think someone is looking right at them. In other words, said the study author, Horstmann, “She’s not looking at you.”

This is ironic (讽刺), because the entire phenomenon of a person’s gaze (凝视) in a photograph or painting seeming to follow the viewer is called the “Mona Lisa effect”, which is absolutely real. If a person is illustrated or photographed looking straight ahead, even people viewing the portrait from an angle will feel they are being looked at. As long as the angle of the person’s gaze is no more than about 5 degrees off to either side, the Mona Lisa effect occurs.

Horstmann and his co-author were studying this effect for its application in the creation of artificial-intelligence avatars (虚拟头像) when Horstmann took a long look at the “Mona Lisa” and realized she wasn’t looking at him.

To make sure it wasn’t just him, the researchers gathered 24 people to view images of the “Mona Lisa” on a computer screen. They set a ruler between the viewer and the screen and asked the participants to note which number on the ruler intersected (相交) Mona Lisa’s gaze. To calculate the angle of Mona Lisa’s gaze as she looked at the viewer, they moved the ruler farther from or closer to the screen during the study. Consistently, the researchers found, participants judged that the woman in the “Mona Lisa” portrait was not looking straight at them, but slightly off to their right.

So why do people repeat the belief that her eyes seem to follow the viewer? Horstmann isn’t sure. It’s possible, he said, that people have the desire to be looked at, so they think the woman is looking straight at them. Or maybe the people who first coined the term “Mona Lisa effect” just thought it was a cool name.

8 . Modern agriculture and its ability to feed billions of people may be one of humanity’s greatest achievements. However, it comes with hidden costs. For example, have you ever considered how much water is needed to provide you with a steak or a salad? It may surprise you.

In a recent study published in the journal Nutrients, scientists from the Commonwealth Scientific and Industrial Research Organization (CSIRO), took a close look at the diets of 9,341 adult Australians – specifically, their “water-scarcity (缺少) footprints”.

The water-scarcity footprint is a widely recognized measurement of water consumption（消耗）. First, it counts the liters of water you used. Then, it looks at the place where the water was used. Using a liter of water in the desert is not the same as using a liter of water in a tropical (热带的) rainforest. The more scarce water is in your area, the larger your water-scarcity footprint.

The scientists found that the average Australian’s diet had a water-scarcity footprint of 362 liters per day. Snacks and beverages – cookies, cakes, sodas and alcohol – accounted for 25 percent of the water-scarcity footprint. The research also included a glass of wine (41 liters), a single serving of potato chips (23 liters), and a small bar of milk chocolate (21 liters). Not surprisingly, cutting out snacks would be the NO.1 priority if you wanted to lower your own water-scarcity footprint.

Climate change is causing droughts and extreme weather. In 2018, Cape Town, South Africa, nearly ran out of water due to a drought. Its freshwater reservoir(水库) stayed at just above 13.5 percent of full capacity. By 2030, a world of about 8.6 billion people will need 35 percent more water, and 50 percent more food, according to the United States National Intelligence Council.

So, we need to watch what we eat, not just for our personal health but for the health of our societies.

9 . Tropical ( 热带的) rainforests are disappearing at an alarming rate, and according to a new report by Rainforest Foundation Norway, humans are to blame. The world’s dependence on coal, farming, beans, palm oil and mining has resulted in two-thirds of Earth’s tropical rainforests being completely destroyed, and the remaining ecosystems being put closer to a tipping point.

Tropical rainforests once covered 14.5 million square kilometers of Earth’s surface, but now, just one-third of that remains undamaged. Of the original area tropical rainforests once occupied, 34% is completely gone and 30% is suffering from damage. All that remains is roughly 9.5 million square kilometers, and 45% of that is in a degraded (恶化) state, the report says.

Researchers blame human consumption for the loss. While agriculture has always been a driving factor of rainforest loss, the report said that energy consumption, international trade and the production of beans and palm oil, logging and mining have been the largest threats (威胁) over the past century. A significant number of US products rely on resources from tropical rainforests. The country heavily relies on palm oil, rubber and cocoa, all of which come from forests around the world. Often, these resources are harvested from illegally destroyed lands.

Tropical rainforests are home to more than half of the Earth’s biodiversity and have more carbon in living organisms than any other ecosystem. In addition to supporting significant animal life, tropical rainforests are also necessary for slowing down global warming. “These unique ecosystems are suffering from constant abuse, through our bottomless appetite for land and resources,” said Anders Krogh, the author of the report. “We expect that upcoming UN climate and biodiversity summits provide specific targets and measures to protect tropical rainforests.”

The researchers also believe that the loss of tropical rainforests puts the whole world at the risk of future diseases. “Huge deforestation (毁林) is violating nature’s natural virus protection systems,” Krogh said. “The outbreak of COVID-19 should bring rainforest protection to the top of the agenda of all policy makers and world leaders concerned about preventing the outbreak of new diseases.”

10 . There are many American expressions about insects - like bees, for example.

You might say you were as busy as a bee if you spent your weekend cleaning your house. In fact, you also might say you made a beeline for something if you went there right away. When we go to see a movie, my friend always makes a beeline for the place where they sell popcorn.

Here is an expression about bees that is not used much any more, but we like it anyway. If something was the best of its kind, you might say it was the bee's knees. Now, we admit that we do not know how this expression developed. If fact, we do not even know if bees have knees!

If your friend cannot stop talking about something because she thinks it is important, you might say she has a bee in her bonnet. If someone asks you a personal question, you might say "that is none of your beeswax." This means none of your business.

Hornets are bee-like insects that sometimes attack people. If you are really angry, you might say you are mad as a hornet. And if you stir up a hornet's nest, you create trouble or problems.

Butterflies are beautiful insects, but you would not want to have butterflies in your stomach. That means to be nervous about having to do something, like speaking in front of a crowd. You would also not want to have ants in your pants. That is, to be restless and unable to sit still.

Here are some expressions about plain old bugs, another word for insects. If a friend keeps asking you to do something you do not want to do, you might ask him to leave you alone or "stop bugging me." A friend also might tell you again and again to do something. If so, you might say he put a bug in your ear.

If you were reading a book in your warm bed on a cold winter's day, you might say you were snug as a bug in a rug. And, if you wish someone good night, you might say, "sleep tight — don't let the bed bugs bite."