Better think twice before choosing a password for email, online bank or shopping. Simple passwords are easy to be stolen.

    A password is like a key to your home. If someone steals it, he'll get chances to steal something else. We use passwords everywhere in our life. We are so used to passwords that we don't pay any attention to them until we lose or forget one.

    A study of 28，000 passwords recently stolen from a popular website showed that people often do the easy thing. It found that 16% took a first name as a password. Another 14% used the easiest keyboard combinations such as “12345678” or QWERTY. 5% of the stolen passwords were names of television shows or stars popular with young people. 3% of the passwords expressed feelings like “I don't care，” “Whatever，” “I love you，” or their opposite, “I hate you.”

    Robert Graham, who did the study, advises people to choose a password that is longer than eight characters with one capital letter and one symbol.

    Of course, safe passwords don't mean those hard to remember. Forgetting your password is sometimes a big headache for you. Maybe, the perfect password is easy for you and hard for others.

Look up in the sky. Do you see any clouds? What do they look like? Some clouds are fluffy(绒毛状的) and white, like cotton balls. Others are dark almost black, and make you hold an umbrella. At sunrise and sunset, clouds can look red, purple, or yellow—as if they were colored with crayons. But what are clouds anyway?

    You can't reach out and touch the clouds, but you can make your own in a bottle.

    You need

    * an adult helper

    * a huge, empty glass jar

    * a metal strainer(过滤器)

    * hot water

    * ice

    Do these

    Step1. Have your helper fill the jar with hot water, leave it there for two minutes, then pour out most of the water. Leaving just an inch or two at the bottom of the jar.

    Step2. It's your turn, put the strainer over the mouth of the jar, fill the strainer with ice. Watch the jar.

    What happened?

    A cloud formed in the jar! Some of the hot water at the bottom of the jar turned into hot water vapor(蒸汽). The water vapor rose and met with the cold air coming off the ice. When the water vapor condensed, it formed a cloud. Hot air rises and carries with it lots of water vapor, the higher the air rises, the more it cools down. Soon the cold air can't hold all the water vapor so it starts turning into tiny water drops, and becomes a cloud.

阅读下面短文，从A、B、C、D四个选项中选出最佳选项。

    Almost everybody in America will spend a part of his or her life behind a shopping cart. They will, in a lifetime, push the shopping carts many miles, but few will know—or even think to ask—who it was that invented them.

    Sylvan N. Goldman invented the shopping cart in 1937. At that time he was in the supermarket business. Every day he would see shoppers lugging groceries around in baskets they had to carry.

    One day Goldman suddenly had the idea of putting baskets on wheels. To create the first shopping cart, Goldman used folding chairs. He out one basket on the seat, and he raised the chair by putting wheels under the legs. The wheeled baskets would make shopping much easier for his customers, and would help to attract more business.

On June 4, 1937, Goldman's first carts were ready for use in his market. He was terribly excited on the morning of that day as customers began arriving. He couldn't wait to see them using his invention. However, Goldman was disappointed. Most shoppers gave the carts a long look, but hardly anybody would give them a try. After a while, Goldman decided to ask customers why they weren't using his carts.

    "Don't you think this arm is strong enough to carry a shopping basket?" one shopper replied.

    Goldman wasn't beaten yet. He knew his carts would be a great success if only he could persuade people to give them a try. To this end, Goldman hired a group of people to push carts around his market and pretend they were shopping! Seeing this, the real customers gradually began copying the phony customers.

As Goldman had hoped, the carts were soon attracting larger and larger numbers of customers to his market. Not only did more people come—those who came bought more. With larger, easier-to-handle baskets, customers unconsciously bought a greater number of items than before.

    Today's shopping carts are five times larger than Goldman's original model. Perhaps that's one reason Americans today spend more than five times as much money on food each year as they did before 1937—before the coming of the shopping cart.

    A new App has been used in South Africa to benefit (有助于)the relationship between wildlife and humans.

    Roadwatch, created by the Endangered Wildlife Trust (EWT),is designed to let drivers   record any roadkill they see on the country's highways.

    It may seem like a strange idea, but EWT says that it could become the perfect platform for receiving important information. Information on where endangered species (物种）are living and the danger that they are under from traffic can help to inform decisions on conservation of matters (物质守恒）in the future.

    People can use the App through Facebook, WhatsApp, SMS and Linkedin to report the   species, location, time and date of the creature that has been seen on the road.

    Wendy Collinson field officer at EWT suggested that it could lead to more people taking care on the roads and paying more attention to animals that may be trying to cross the roads. One of the biggest problems is with reptiles (爬行动物）and snakes, which she believes people hit on purpose, as they are generally seen as scary. However, they are important to the health of ecosystems, just as all creatures are and also need to be protected.

    Emily Taylor from EWT said, “Roadkill simply hasn't been studied here. The road ecology and how many endangered species are being killed, is something we need to know more about. We want people to report as much as possible.”

    There have been some other Apps to use in relation to wildlife spotting in South Africa, but most of them are about animals that have not been knocked down, including those helping to collect information of where certain species have been seen, such as in parks.