There are lots of insects that farmers hate. But there also are some they like. They protect crops against damage from other insects. A good example is the lady beetle, which is also known as the ladybug(瓢虫)．

    Lady beetles are a natural control for aphids(蚜虫). Lady beetles are red, orange or black. They often have black spots, though some have light colored spots. Different kinds of lady beetles have different numbers of spots. There are lady beetles with four, five, seven and fourteen spots.

    Many of the well-known kinds of lady beetles come from Asia or Europe. They now are common throughout the United States.

    American scientists imported one kind of lady beetle, the multicolored Asian lady beetle, as early as 1916. They released them as an attempt to control some kinds of insects. Over the years, the beetle has become established, possibly helped by some that arrived with imported plants on ships.

    Experts say over 450 kinds of lady beetles are found in North America. Some are native to the area. Others have been brought from other places. Almost all are helpful to farmers.

    The Asian lady beetles now in the United States probably came from Japan. The Asian lady beetle eats aphids that damage crops like soybeans, fruits and berries.

    In the southern United States, Asian lady beetles have reduced the need for farmers to use reskilling poisons on pecan trees. This popular tree nut suffers from aphids and other pests that the lady beetles eat.

    But some people say the Asian lady beetle has itself become a pest. They worry that the lady beetles may eat their late autumn fruit crops.

    Experts say Asian lady beetles may appear in large numbers in some years. But they say the insects are too helpful to be considered as pests.

    Sports shoes that work out whether their owner has done enough exercise to warrant(保证；授权) time in front of the television have been invented in the UK.

    The shoes — named Square Eyes — contain an electronic pressure sensor and a tiny computer chip to record how many steps the wearer has taken in a day. A wireless transmitter(传话器) passes the information to a receiver connected to a television, and this decides how much evening viewing time the wearer deserves, based on the day's efforts.

    The design was inspired by a desire to fight against the rapidly ballooning waistlines among British teenagers, says Gillian Swan, who developed Square Eyes as a final year design project at Brunel University to London, UK. “We looked at current issues and childhood overweight really stood out,” she says. “And I wanted to deal with that with my design.”

    Once a child has used up their daily allowance gained through exercise, the television automatically switches off. And further time in front of the TV can only be earned through more steps.

    Swan calculated how exercise should translate to television time using the recommended daily amounts of both. Health experts suggest that a child take 12,000 steps each day and watch no more than two hours of television. So, every 100 steps recorded by the Square Eyes shoes equals exactly one minute of TV time.

    Existing pedometers(计步器) normally clip(夹在) onto a belt or slip into a pocket and keep count of steps by measuring sudden movement. Swan says these can be easily tricked into recording steps through shaking. But her shoe has been built to be harder for lazy teenagers to cheat. “It is possible, but it would be a lot of effort,” she says. “That was one of my main design considerations.”

    We humans spend about one-third of our lives asleep. This may sound like a lot of time, but it is not wasted. Sleep not only helps us stay healthy but it also helps our brains remember. Our brains need good sleep to remember what we do and learn during the other two thirds of our lives when we are awake.

    Researchers at the University of Wisconsin-Madison have found that sleep helps improve brain performance by shrinking(收缩)synapses in the brain. A synapse is the area where cells pass messages to other cells.

    Scientist Chiara Cirelli is a leader at the school's Center for Sleep and Consciousness. She told the reporter that sleep is when the human brain mixes information it has learned while awake into its general collection of knowledge. Meanwhile, the brain forgets unimportant details. This forgetting is important. It makes space for new learning and new memories.

    Cirelli said that the Centers research began with this hypothesis(假设): We sleep so that our brain can repair and refresh itself. She said the idea seems simple and reasonable. However, testing and discovering how it works has been extremely difficult.

    Synapses are only about 20-40 nanometers(纳米)wide. The team began their study by measuring the size of the synapses to look for changes in these already tiny spaces between nerve cells. Cirelli says the process(过程) is difficult because"all the actual measurements of the synapses have to be done by hand." The team had to wait until improvements in laboratory technology made it possible to see these tiny changes. A University of Wisconsin press release called the research a"huge job." Many research specialists worked for four years to photograph, rebuild and study certain areas of a mouse brain. The report also said the scientists measured 6,920 synapses.

    Cirelli says they found that our synapses shrink as our brains clean themselves during sleep. We wake up refreshed and ready to fill those synapses with new information. The research findings are the result of years of hard work at the University of Wisconsin Madison. The researchers published their findings in the journal Science.

    I travel a lot, and I find out different “styles” of directions every time I ask “How can I get to the post office?”

    Foreign tourists are often confused in Japan because most streets there don't have names; in Japan, people use landmarks（地标）in their directions instead of street names. For example, the Japanese will say to travelers, “Go straight down to the corner. Turn left at the big hotel and go past a fruit market. The post office is across from the bus stop.”

    In the countryside of the American Midwest, there are not usually many landmarks. There are no mountains, so the land is very flat; in many places there are no towns or buildings within miles. Instead of landmarks, people will tell you directions and distances. In Kansas or Iowa, for example, people will say, “Go north two miles. Turn east, and then go another mile.”

    People in Los Angeles, California, have no idea of distance on the map; they measure distance in time, not miles. “How far away is the post office?” you ask. “Oh,” they answer, “it's about five minutes from here.” You say, “Yes, but how many miles away is it?” They don't know.

    It's true that a person doesn't know the answer to your question sometimes. What happens in such a situation? A New Yorker might say, “Sorry, I have no idea.” But in Yucatan, Mexico, no one answers “I don't know.” People in Yucatan believe that “I don't know” is impolite. They usually give an answer, often a wrong one. A tourist can get very, very lost in Yucatan!

    In the future we might live somewhere other than Earth, like Mars. Some people ask how this will be possible. Well, Mars is in fact a lot the same as the earth. The days are almost the same as those on the earth. However, the two planets vary in temperature.

    Since there is mostly carbon dioxide on Mars, it would be quite difficult for a human to just land on it. So, special types of homes and space suits have to be designed. The space suits should be almost like the ones astronauts use now, and except that they have to be warmer so that the astronauts can survive the cold temperatures. The space suits must also be able to withstand (承受) high pressure and potentially dangerous radiation that can kill.

    The houses should be similar to our homes today with a slight difference. All of the houses and other buildings should be built inside a large dome (圆顶状物) or bubble. The domes should be made out of glass, and would also be able to prevent radiation from affecting the people inside. The domes will be connected to a machine (like plants which turn carbon dioxide into oxygen).

    With Mars' population growing, how would the people on its surface get fresh food and water? Just like humans use domes, they can also use domes to grow plants. However, the domes where the plants are grown must be built to expand. Once we upgrade the domes to a larger size then we can grow more food by cultivating (种植) more plants. To get the food or come in connect with other domes, there will be long narrow tunnels like roads that connect to each dome separating them by several doors so that the pressure in each dome can remain the same.

    On Mars, so many other things are available to us. As humans, we can have access to rare and fairly expensive metals that aren't very easy to get hold of on Earth, and a colony on Mars enhances (提高) our chances of finding these metals. So when someone here on Earth says that going to Mars is impossible, please tell them that they'll never know it until they try and they may try very soon. After all it's our future. Why not make it on Mars?

    Many of us deal with mental health challenges on a daily basis. Being fed a steady diet of destructive world events only serves to make that harder, So I've decided to share a few strategies to avoid being completely broken down by the newsfeed right now.

    {#blank#}1{#/blank#}

    You'll find it easier to make this mental mindshift if you make a conscious effort to boost your level of positive emotion by doing things you enjoy and spending time with people you love. Positive emotions leave the door open to possibility while negative emotions keep the door shut.

    Recognize that there's a difference between being absorbed and being informed

    Sure, you want to be aware of what's happening in the world, but that doesn't mean that you have to be absorbed into your Twitter or Facebook and aim for a balanced media diet.{#blank#}2{#/blank#} Move toward the good, too.

    Look for opportunities to take action

    {#blank#}3{#/blank#} But by carrying through on sort of positive action, however small (writing a letter, making a donation, attending a face-to-face get-together in your town), you'll feel good. And that will help to stop what can otherwise quickly change into negative feelings of anxiety and sadness.{#blank#}4{#/blank#}

    Reach out-don't break down Inward

    Connect with other caring citizens who share your concern about what's happening in our country and our world. Talk to other people you know who may be going through an especially difficult time right now.{#blank#}5{#/blank#}Finally, reach out for other types of support if you feel like you're really struggling.

A. It doesn't have to be something huge.

B. Say no sometimes.

C. Hold your sense of optimism.

D. Let them know that you will be there to support them and that you care.

E. Feeling powerless fuels anxiety, taking action brings it down.

F. Don't just focus on the really bad news.

G. Doing good deeds can also relax social anxiety.