【推荐2】“Zero calories(卡路里) and no weight gain.” Diet soft drinks(无糖饮料) are often advertised in this way. But are they really a good choice for us?

Some people think diet soft drinks are healthier because they don’t have any sugar or calories. They think drinking these drinks can help them to lose weight.

Actually, diet soft drinks do have some sugar, although very little. Usually, if there is 0.5 grams of sugar or less in a 100-gram drink, it can be described as a diet soft drink.

Although they have little sugar, diet soft drinks still taste sweet by using artificial sweeteners(人工甜味剂). They have very few calories.

Sugar just tastes good. Sweet is the first taste that people start to enjoy after birth. So when you eat sweet-tasting things like sugar, our brains start to want more of it. The taste of sugar also releases endorphins(分泌内啡肽) that calm and relax us. It also hits your brain and makes you want more. Your brain tells your body to prepare itself for more sugar. When you drink a diet soft drink, the brain receives the “sweet signal”, but no sugar arrives. Since the brain is fooled, it still wants more sweets.

Some people drink diet soft drinks instead of water. This is not a good choice. Diet soft drinks can be bad for your teeth and affect your appetite(食欲). The additives(添加剂) in these drinks are not good for you either.

【推荐3】Different weather makes people feel different. It influences health, intelligence (智力) and feelings.

In August, it is very hot and wet in the southern part of the United States.People there have heart trouble and other kinds of health problems during this month.In the Northeast and the Middle West, it is very hot at some times and very cold at other times.People in these states (州) have more heart trouble after the weather changes in February or March.

The weather can also influence intelligence. For example, in a 1983 report by scientists, IQ (智商) of a group students was very high when a very strong wind came，but after the strong wind, their IQ was 10% lower.The wind can help people have more intelligence. Very hot weather, on the other hand，can make it lower.Students in many schools of the United States often get worse on exams in the hot months of the year (July and August).

Weather also has a strong influence on people's feelings.Winter may be a bad time for thin people.They usually feel cold during these months.They might feel unhappy during cold weather.But fat people may have a hard time in hot summer.At about 18℃，people became stronger.

Low air pressure (气压) may make people forgetful (健忘). People leave more bags on buses and in shops on low­pressure days.People feel best at a temperature of about 18℃.

Are you feeling sad, tired, forgetful, or unhappy today? It may be the weather's problem.

【推荐1】When we see babies or pets, we can’t help gently touching them to show our love. And they give us happy feelings back. But a recent study shows that it’s different for plants.

In fact, ▲ . That’s because touching changes their genes and, even worse, can slow their growth. Professor Jim Whelan of the La Trobe Institute in Australia gave an explanation. “The lightest touch from a human, or even plants touching each other in the wind, leads to a huge gene change in the plant.”

In order to test the idea, the scientists did an experiment on plants. They grew a number of plants to the age of four weeks. Then they touched them with a paintbrush every 12 hours over a 36-hour period. They found that as a result, the mitochondria in the plants had been partly hurt. The mitochondria are the “powerhouse of the cell”. The mitochondria produce energy for the rest of the cell in both animals and plants. If this “powerhouse” is weakened, the plants will lose a large amount of energy that should have supported their growth. Whelan further explained, “If the touching is repeated, then plant growth is reduced* by up to 30 percent.” According to Science Alert, repeated touching or moving plants will make them grow shorter than others.

Although the touching does have a strong effect on plants, it’s not always bad. The researches believe, in some way, it could be helpful. It may help plants fight against insects and bad weather. The new research findings have led to a deeper understanding of the plants’ reply to touching. And the research might also “open up new ways to optimize growth in the future.” Science Alert reported.

【推荐2】Many cultures have stories of talking trees that give advice as well as warnings to people. Alexander the Great and Marco Polo were said to have visited such a tree in India. And in some modern stories, such as the film Avatar, trees can communicate with animals and people. With our long believing that talking plants are unreal, new research has found something amazing: It turns out that plants can really communicate.

It has been known that plants use chemicals to communicate with each other. This happens when a plant, say a bean plant, gets attacked by insects. The plant gives off chemicals from the leaves that are being eaten. This is like a warning, or a call for help, “I’m being attacked!” When another bean plant feels the chemicals from its poor neighbor, it starts to give off its own, different chemicals. Some of these chemicals drive insects away. Others attract insects—the wasps! The wasps kill the insects that are eating the bean plant. Scientists hope to learn more about this plant warning system, so that we can use it to grow crops without pesticides (杀虫剂).

More surprisingly, plants also use sounds to communicate. People can’t hear these sounds, but plants are making them. Some plants make noises with their roots. Corn and chili plants do this. They also “listen” to the noises from other plants. A chili plant can tell if a neighboring plant is helpful, or unfriendly. Some trees make clicking noises when there is not enough water.

Most surprisingly of all, plants have an amazing system of communication that can link nearly every plant in a forest. Scientists call this system “wood wide web”. It is in some ways like the Internet we use. This wood wide web is linked underground by fungi (真菌). Using this wood wide web, plants can share information and even food with each other. But just like our Internet, this wood wide web has its own version of “cybercrime (网络犯罪)”. Plants can steal food from each other, or spread something harmful to attack other plants.

Scientists are learning more every day about the secret ways in which plants talk to each other. Maybe we will know enough about plant communication to be able to “talk” with them ourselves in the near future. Let’s wait and see.

【推荐3】Do you know that some strange plants even eat insects (昆虫) or small animals? These plant can’t get enough food from the ground, so they need to eat something else.

A kind of plant smells very sweet and its leaves are red. Many insects love bright colors like red. When they see the red leaves on this plant, they fly down for supper! But the leaves have lots of long hair on them. If an insect touches the hair, the two sides of the leaf shut (合上) together at once. It takes less than half a second! The poor insect is now inside the leaf and cannot get out. It becomes food for the plant. The plant eats it slowly. It takes the plant about 12 to 15 days to finish its meal.

Some small plants can catch insects, but a few big ones can even catch small animals. Another kind of plant has special leaves with hair on them. The hair shines (发光). When insects or animals see the shiny leaves, they come to have a look. If an insect jumps onto a leaf, it gets caught by the hair. The hair moves very quickly and holds the insect so it cannot move. Then the leaf closes round it, and the plant begins to eat at once.