We always think that it's OK for us to leave our plants home during our vacation as plants won't scream like pets, right?

    A recent study done by a group of scientists at the Tel Aviv University has discovered that some plants will scream when they are under stress.

    The research was carried out on tomato plants and tobacco plants by cutting their stems (茎) and depriving (剥夺) them of water. A microphone was placed 10cm away from them. When their stems were cut, the plants started "screaming" between 20 and 100 kilohertz, and the scientists guess that this scream is probably meant to warn other plants nearby.

    When the tomato plants' stems were cut, 25 ultrasonic (超声的) pain sounds were recorded in an hour, and at the same time, 15 ultrasonic pain sounds were recorded from the tobacco plants. When they were deprived of water, the tomato plants recorded even more pain sounds with 35 pain sounds in an hour while the tobacco plants recorded about 11 pain sounds.

    The plants also acted differently to different kinds of stresses. For example, the tobacco plants gave out a stronger "scream" when they were deprived of water than when their stems were cut. But plants that were in no immediate (立刻的) danger gave out less than one ultrasonic sound per hour.

    The group of scientists said that plants are not as quiet as we had always thought, but in fact their voices are so high-pitched that we just can't hear them.

    Last year, another study has found out that plants feel pain when they are touched or hurt and they will give off a terrible smell.

"Happiness is a habit," says Talia Soen, CEO of Happy Things, a platform (平台) that helps you develop those habits through daily lives. "Many people think happiness is hard to achieve, but we want to make it easy to understand and teachable." she says, "Let's examine the habits of happy people."

The experience of joy is related to the good, meaningful life. Happiness can be found in the small moments of our daily lives. For example, showing thankful feeling has been proved to increase happiness. Take a moment to think about the help you receive from others and thank them deeply. It can bring great joy to your life.

Reducing stress can improve your overall happiness. It's not a good idea to worry about too much. Soen suggests that spending time in nature is helpful for stress reduction. Even if you don't have time or access to go outdoors all year round, you can feel better by listening to nature sounds. And a study has shown that people feel less stressed if they have two to five hours of free time every day.

"There have been several studies on happiness and exercise," Soen says. "Many studies show that our happiness levels are influenced by moving our bodies a little bit more." The exact reason remains unclear, but even short periods of exercise can achieve this. As Soen mentioned earlier, exercising outdoors can have a double influence.

Having strong social relationships, such as friends, family, or other meaningful connections, can contribute to happiness. These relationships provide support when you need it. A researcher says, "Happy people spend more time with their friends and family members and are simply around other people more often." So, why not have lunch with your family or reach out to an old friend?

As you can see, happiness is all around us as long as we develop good habits.

Niger, in central Africa, is a country with very little rain. 80% of people have no running water at home. So water is very important in {#blank#}1{#/blank#} (people) life, but sometimes it means that kids don't do {#blank#}2{#/blank#} (good) at school.

Children often have to travel far to find water {#blank#}3{#/blank#} the family. Sani, 11, gets water in the morning and {#blank#}4{#/blank#} (be) usually late for school. "Some of the other children are {#blank#}5{#/blank#} (luck)," he says. "They don't have to get water. So they learn {#blank#}6{#/blank#} (quickly) than me." One girl, Badjeba, says, "Yesterday, I got up at 4:30 to get water. Then I took it home and {#blank#}7{#/blank#} (walk) to school. I was really tired, so I fell asleep in the lessons."

In one classroom, {#blank#}8{#/blank#} old teacher asks: "How many of you were late today {#blank#}9{#/blank#} you had to get water?" And about 90% of the kids put their hand up. {#blank#}10{#/blank#} (They) families send them to get water-school is important, but water is life.

What's the weather going to be like tomorrow？In fact，we can know it by checking out nature. 

Want to know how hot it is outside？Listen to a cricket （蟋蟀）!The more it sings in a minute，the hotter it is. Spiders（蜘蛛） can make a prediction of cold weather. If you find a lot of spiders inside your house，it means it might get cold soon. Spiders go indoors when the weather is cool，so be careful with them in the dark places of your home. 

Pine cones （松果） can tell whether dry weather is coming. Pine cones open their scales （鳞片） when the weather gets very dry. They do this to spread seeds（传播种子）. When the air is a little wet，they close up to keep their seeds dry. Pine seeds travel by wind，so they have to stay as dry and light as possible in order to fly. 

Nature is man's teacher. Man should protect the nature，and man should get along well with it. There is much more that people can learn from nature. 

Driving an electric car is good for the environment(环境). But is that true?

A University recently studied emissions (排放物) from different cars. The   scientists found that sometimes electric cars were worse for the environment than other cars. Surprising Well, please pay attention to the word " sometimes". Electric cars should be clean. The problem lies in th power(动力). If the power comes from the wind or the sun, electric cars will be good far the environment But if the power is from coal(煤炭), it will bring a co ntrary situation. According to the study, emission from these electric cars kill about 3,000 people a year. Compared with it, emissions from other cars makes about 880 people's death a year.

In France, more than half of the power comes from nuclear(原子核的) stations. Electric cars there should be as clean as they can be. But in many other countries, coal is still the main source(来源) of electricity. India, for example, needs coal for 61% of its power. Only 2% of its electricity comes from nuclear sources. In countries like India, electric cars are not clean at all!

All in all, sellers are not lying(说谎) when they say electric cars are clean, but they are right only when the power is also clean.

International(国际的) Nurses Day falls on May 12 every year. It is in memory of the birth of Florence Nightingale. Who was this lady?

Nightingale was one of the most important health workers in history. During a war(战争)in the 1850s，she worked with other nurses to care for English soldiers(士兵). She set many important rules for health care. Because of her habit of making rounds(巡诊) at night，people called her "the Lady with the Lamp(灯)". Later in 1860，Nightingale opened a health care school in London. She trained many excellent nurses in this school. 

Every year on this festival for nurses，a special activity is held in London. A lamp is handed from one nurse to another. This means that knowledge is passed from one nurse to another. 

Nurses make up more than half of all health workers，but there are still 5. 9 million more nurses needed in the world. The terrible disease(疾病) has reminded us of the importance of nurses. Without nurses and other health workers，we wouldn't be able to fight against diseases successfully.