【推荐1】What color is a tennis ball? Ask your classmates, and they might give you some surprising answers.

US magazine The Atlantic recently asked 30,000 people this question. Among them, 52 percent said tennis balls are green, 42 percent said they are yellow, and 6 percent went with other colors. According to the International Tennis Federation, tennis balls are yellow.     1    

Scientists call this color constancy (色彩恒常性). For example, we know that China's flag is red. When we see it during sunset or under purple light, we still know that it is red, even if it looks like a different color.     2     Even if the object is seen in different kinds of light later, our brain can still tell its true color.

    3     It appears to be a combination of yellow, a ''warm'' color and green, a ''cool'' color.

According to The Atlantic, when our brains try to figure out what color the ball is, some people ignore ''cool'' colors, such as green, blue and purple. So they see the ball as being yellow.    4     They see the ball as being green.

    5     In 2015, a girl posted a picture of a dress online. Some people believed the dress was black and blue—but others thought it was gold and white. They had different opinions based on whether they ignored ''cold'' or ''warm'' colors.

【推荐3】Brriiinnng... ... The alarm clock announces the start of another busy weekday in the morning. You jump out of bed, rush into the shower，into your clothes and out the door with hardly a moment to think. A stressful journey to work gets your blood pressure climbing. Once at the   office, you glance through the newspaper with depressing stories or reports of disasters. In that sort of mood，who can get down to work, particularly some creative, original problem-solving work?

The way most of us spend our mornings is exactly opposite to the conditions that promote flexible,open-minded thinking. Imaginative ideas are most likely to come to us when we’re unfocused. If you are one of those energetic morning people, your most inventive time comes in the early evening when you are relaxed. Sleepy people’s lack of focus leads to an increase in creative problem solving. By not giving yourself time to tune into your wandering mind, you’re missing out on the surprising solutions it may offer. The trip you take to work doesn’t help, either. The stress slows down the speed with which signals travel between neurons(神经细胞)，making inspirations less likely to occur. And while we all should read a lot about what’s going on in the world, it would not make you feel good for sure, so put that news website or newspaper aside until after the day’s work is done.

So what would our mornings look like if we wanted to start them with a full capacity for creative problem solving? We’d set the alarm a few minutes early and lie awake in bed，following our thoughts where they lead. We'd stand a little longer under the warm water of the shower，stopping thinking about tasks in favor of a few more minutes of relaxation. We’d take some deep breaths on our way to work, instead of complaining about heavy traffic. And once in the office —we’d click on links not to the news of the day but to the funniest videos the web has to offer.

【推荐2】Many animals move from one place to another at certain times of the year. This yearly movement is called migration (迁徙). They migrate to find food, a partner or warmer climate. One of the most wonderful migration in nature is that of the North American monarch butterfly (帝王蝴蝶).

Every autumn, millions of these beautiful insects with fine black and orange wings begin a long and difficult journey. Somehow they manage to travel around 4,000 kilometers south and find their way to California or Mexico. However, until recently no one knew how they did this.

A team of scientists led by Professor Eli Shlizerman at the university of Washington has now found the answer. They have found out that the monarch is able to tell the time of day. It uses its eyes to measure the position of the sun. These two pieces of information—the time of day and the point where the sun is in the sky—allow the butterfly to determine the way to go. Finally, it manages to reach the places where it will spend the winter.

The solution to the mystery of the monarch’s amazing ability comes at a time when it is in serious trouble. Its population has crashed by as much as 90 percent in the last few years. Sadly, human activity is the main reason why the number of monarch butterflies is decreasing. In many of the places where the butterfly can be spotted, people are destroying the natural environment. They cut down trees and use chemicals that kill the plants that monarch caterpillars (幼虫) feed on.

The research on the monarch’s behavior has however led to a greater awareness of this creature. People have been working together to record its migration and make sure that there are enough plants for it to eat. If this works, there may come a time when the number of monarch butterflies increases once again. The more we know about this lovely creature, the greater the chance it will survive to keep its place in the natural world for a long time to come.

【推荐3】Any 25th birthday is a cause for celebration. But it was even more so for Janus, a two-headed Greek tortoise (龟). Living in the Natural History Museum of Geneva, Switzerland, Janus is now believed to be the world’s oldest two-headed tortoise. The museum celebrated the special occasion with a day-long party filled with fun events, which included taking photos with the birthday “boy”.

In the wild, Greek tortoises can live up to two hundred years in their natural habitat. However, two-headed tortoises, like Janus, usually do not survive for that long. Unlike normal tortoises, they are unable to take back their two heads into their shell, making them highly easy to be attacked.

Janus, who has spent his entire life in the museum, faces no such danger. But life is not without challenges for the two-headed tortoise who also has two hearts and two pairs of lungs. Each head controls the front and back legs on its side of the body. The right head is more curious and more awake. The left head is more passive and loves to eat. This can lead to confusion when the two heads decide to go in different directions. To make matters worse, the two heads frequently rub against each other, resulting in skin sores (溃疡). Janus also has a hard time rolling back onto his feet when he accidentally turns over. If left on their backs for too long, tortoises can get sunburned, dehydrated (脱水的) and even die.

Fortunately, Janus has a special caregiver, Angelica Bourgoin, to make sure he lives a long and healthy life. The tortoise receives a daily massage and is bathed in green tea and flower water. He eats a special diet of organic fruits and vegetables, keeps active with walks, and rides on his skateboard. With such loving care, the two-headed tortoise will surely continue to break many more records for long life.