4 . We’ve known for years that plants can see, hear, smell and communicate with chemicals. Now, reported New Scientist, they have been recorded making sounds when stressed.

In a yet-to-be-published study, Itzhak Khait and his team at Tel Aviv University, in Israel, found that tomato and tobacco (烟草) plants can make ultrasonic (超声的) noises. The plants “cry out” due to lack of water, or when their stems (茎) are cut. It’s just too high-pitched (音调高的) for humans to hear.

Microphones placed 10 centimeters away from the plants picked up sounds in the ultrasonic range of 20 to 100 kilohertz (千赫兹). Human hearing usually ranges from 20 hertz to 20 kilohertz. “These findings can change the way we think about the plant kingdom,” they wrote.

On average, “thirsty” tomato plants made 35 sounds an hour, while tobacco plants made 11. When plant stems were cut, tomato plants made an average of 25 sounds in the following hour, and tobacco plants 15. Unstressed plants produced fewer than one sound per hour, on average.

Perhaps most interestingly, different types of stress led to different sounds. The researchers trained a machine-learning model to separate the plants’ sounds from those of the wind, rain and other noises of the greenhouse. In most cases, it correctly identified (辨识) whether the stress was caused by dryness or a cut, based on a sound’s intensity(强度) and frequency. Water-hungry tobacco appears to make louder sounds than cut tobacco, for example. Although Khait and his colleagues only looked at tomato and tobacco plants, they think other plants also make sounds when stressed.

If farmers could hear these sounds, said the team, they could give water to the plants that need it most. As climate change causes more droughts (旱灾), they said this would be important information for farmers. “The sounds that drought-stressed plants make could be used in precision agriculture (精准农业),” said Anne Visscher at the Royal Botanic Gardens, Kew, in the UK.

Khait’s report also suggests that insects and mammals (哺乳动物) can hear the sounds up to 5 meters away and respond. For example, a moth (蛾子) may decide not to lay eggs on a water-stressed plant. Edward Farmer, at the University of Lausanne, Switzerland, is doubtful. He said that the idea of moths listening to plants is “a little too speculative”.

If plants are screaming for fear of their survival, maybe we should be glad we can’t hear them.

5 . Unlike any other art form, movies require hundreds of people and piles of money. With such financial risks, studios (电影公司) want to attract as many people as possible and make a big profit（利润）. I often complain that chasing profits ruins movies. Imagine if Italian painter Leonardo da Vinci (1452-1519) had to satisfy investors for The Last Supper.

In May, Paramount released（发行） its trailer (预告片) for a live-action Sonic the Hedgehog movie. Everyone was excited – me too! I love this character, in part because he’s ridiculous（荒谬的）. Hedgehogs (刺猬) aren’t fast, nor are they blue. Had the game’s designers ever actually seen a hedgehog? Who cares? Sonic has always looked cool. Nobody would play a video game featuring a realistic hedgehog character.

When I saw the movie trailer, though, I worried. Sonic’s eyes were too far apart and his big teeth looked like they would eat my fingers. His body looked like a child wearing pajamas 睡衣）. Sonic didn’t look cool. He looked like the half-human result of a failed genetic (基因的) experiment.

You know the internet. People there will fight you for saying the sky is blue. This time, however, the internet stood together: Sonic looked TERRIBLE. People joked about it all over social media. Paramount couldn’t ignore this online outrage（愤怒） and quickly announced a redesign, at great cost to the company.

At first, I thought it was awesome. Back when I was a kid, there was no social media. We would have been stuck with creepy, crappy (怪异且蹩脚的) Sonic and his terrifying teeth. After the redesign, Sonic looks cooler than ever. I’m glad the studio broke its budget to get Sonic right.

But I’m a little worried, too. What if this starts a trend(趋势)? What if directors keep going to Sina Weibo or Twitter to make people happy? One thing I’ve learned in life is that if you try to make everybody happy, nobody will be happy.

If an art form only exists to make money by giving audiences what they expect, can we really call it “art” anymore? Some of my favorite movies are ones that nobody liked at first. Usually, what makes them good is the same thing that made them unpopular. Studios might end up with lots of money but we would end up with a lot of bad movies.

The term “helicopter（直升机） parents” is a description of parents who are hovering(盘旋) over their children in a state of extreme concern. They always show up to solve their children’s problems, protect them from real or imagined harm, resolve stressful situations, offer advice and get them out of trouble, even if they behave wrongly. Although out of love and concern, it can have harmful effects on their children’s emotional development and future independence.

Children learn through their mistakes. But if you intervene(干涉，介入) at first sign of struggle and finish your child’s homework, he’ll miss out on valuable learning opportunities.

You’re sending him the message that he needs to be perfect and failure is not an option; otherwise you wouldn’t always take over from him.

By constantly rescuing your child from stressful situations, you’re sending him a message that you don’t believe he’s able to take care of himself. Children develop self-esteem(自尊) by learning how to complete challenges on their own. If you are always intervening, he will miss this vital stage in his growth. As a result, your child may lack the confidence necessary to do well in school, pursuing hobbies and interests, and developing friendships.

If you’re always taking care of everything for your child, it’ll be more difficult for him to become independent. As an adult, he might find it hard to take care of himself, because he has never developed coping skills to deal with life’s challenges. He might suffer from irrational(不理智的) fears, anxiety and depression, which could lead him to drop out of college or frequently change jobs, according to Dr Michele Borba. Instead of developing healthy relationships, he might seek a partner who will take care of or control him, as his parents did.

You can help your child become more independent by allowing him to complete tasks and challenges on his own without your intervention. Even if he fails at first, don’t interfere(干涉，干预) — encourage him to start again. Show that you have faith in his abilities to succeed without your help. Allow him to learn natural consequences（后果）. Even small things can help him become more independent— making his own bed, preparing his own lunch, shopping for his own clothes and doing homework without your help.

Yours,

Li Hua

8 . Earthquake rescue robots have experienced their final tests in Beijing.Their designers say with these robots,rescuers will be able to buy more time to save lives during an earthquake.

This robot looking like a helicopter,is called the detector-bot.It’s about 4 meters long,and it took about 4 years to develop the model.Its main functions are to collect information from the air,and send goods of up to 30 kilos to people trapped by an earthquake.

This robot has a high definition 360 degrees panoramic (全景) camera.It can work day and night and will also be able to send the latest pictures from the quake area.

Dr.Qi Juntong,Chinese Academy of Science,said,“The most important feature of this robot is that it doesn’t need a distant control.We just set the destination (目的地) information on it,and then it takes off,and lands by itself.It flies as high as 3,000 meters,and as fast as 100 kilometers per hour.”

This robot has a different function—it can change as the environment changes.Its main job is to search for any signs of life in places where human rescuers are unable to go.

As well as a detector (探测器) that finds victims and detects poisonous gas,a camera is placed in the 40 centimeters long robot, which can work in the dark.

Another use for the rescuers is the supply bot.With its 10-meter-long pipe,people who are trapped in the ruins,will be able to get supplies including oxygen and liquids.

Experts have said that the robots will enter production,and serve as part of the national earthquake rescue team as soon as next year.