E-mail systems at thousands of companies and government offices around the world were attacked by a virus(病毒)called “Melissa” that disguises(伪装)itself as an “important message from a friend. In spite of a weekend of warnings，more than 50 000 computers at about 100 places around the world have been attacked by the virus，computer security experts said on Monday.

    The virus began to show up last Friday and spread rapidly on Monday by making computers fire off dozens of infected(被传染的)e-mails. Although the virus causes no serious damage to a computer，its effect was far reaching.

    To make matters worse，a similar virus called “Papa” was discovered on Monday. Papa is programmed to send out even more infected e-mails than Melissa.

    The Melissa virus comes in the form of an e-mail，usually containing the subject line“Important Message”. It appears to be from a friend. The body of the e-mail message says，“Here is that document you asked for...,don't show it to anyone else.” Attached(附)to the message is a document file.

    Once the user opens that file，the virus digs into the user's address book and sends infected documents to the first 50 addresses. E-mails from the Papa virus include an attached spreadsheet(电子数据文件)file. When the user opens that file，the virus sends 60 infected e-mails.

    The reason why this is spreading so fast is that you are getting it from people you know. You should never open documents or attachments from people you don't know. People who get an unexpected e-mail with the “important message” subject line should delete it immediately and not open the message.

    Chinese scientists recently have produced two monkeys with the same gene, Zhong Zhong and Hua Hua, using the same technique that gave us Dolly the sheep. These monkeys are not actually the first primates(灵长类)to be cloned. Another one named Tetra was produced in the late 1990s by embryo(胚胎)splitting, the division of an early-stage embryo into two or four separate cells to make clones. By contrast, they were each made by replacing an egg cell nucleus(原子核)with DNA from a differentiated body cell. This Dolly method, known as somatic cell nuclear transfer(SCNT), can create more clones and allows researchers greater control over the edits they make to the DNA.

    Success came from adopting several new techniques. These included a new type of microscopy to better view the cells during handling or using several materials that encourage cell reprogramming, which hadn't been tried before on primates. Still, the research process proved difficult, and many attempts by the team failed. Just two healthy baby monkeys born from more than 60 tested mothers. This leads to many researchers' pouring water on the idea that the team's results bring scientists closer to cloning humans. They thought this work is not a stepping stone to establishing methods for obtaining live born human clones. Instead, this clearly remains a very foolish thing to attempt, it would be far too inefficient, far too unsafe, and it is also pointless.

    But the scientists involved emphasize that this is not their goal. There is now no barrier for cloning primate species, thus cloning humans is closer to reality. However, their research purpose is entirely for producing non-human primate models for human diseases; they absolutely have no intention, and society will not permit this work to be extended to humans. Despite limitations, they treat this breakthrough a novel model system for scientists studying human biology and disease.

    To travel abroad, we often meet the problem of what to take and how to take it. Take as little as possible. Choose clothes for your use in different kinds of situations and when you have made your final choice, take half of it! It's always a big problem to take too many things, and anyway if necessary, you can buy what you need in America. Things like jeans, T-shirts and other clothes are good buys in the US. If you hunt around you can usually find something on sale.

    Whatever baggage you take, make sure it is easy to take. Getting on and off buses and trains, even just changing planes, can be a test if your bags are too heavy or too many. The best way is to take one holdall, like a suitcase or a backpack, and then a smaller bag. Even when you have to check in your holdall, at the airport or bus station, you can keep all your money and documents by your side. It is also a good idea to keep a change of clothing in your shoulder bag in case your suitcase or backpack gets lost by an airline or a bus company.

The means you choose to travel around the US will depend on your money, you time and something else. Since there are certain discounts available to travelers who buy their tickets outside the US, it is a good idea to make travel plans before you go. Also, when you buy your tickets outside the US, you save the eight percent sales tax. Travel is like everything else in America—you have to shop around for the best busy. Never be afraid to ask for the cheapest fare. The clerk seldom offers you the cheapest one.

    In Canada, rights come with responsibilities. These include:

Obeying the law—one of Canada's founding principles is the rule of law. Individuals and governments are regulated by laws and not by arbitrary actions. No person or group is above the law.

    Taking responsibility for oneself and one's family—getting a job, taking care of one's family and working hard in keeping with one's abilities are important Canadian values. Work contributes to personal dignity and self -respect, and to Canada's prosperity.

    Serving on a jury—when called to do so, you are legally required to serve. Serving on a jury is a privilege that makes the justice system work as it depends on impartial juries made up of citizens.

    Voting in elections—the right to vote comes with a responsibility to vote in federal provincial or territorial and local elections.

    Helping others in the community—millions of volunteers freely donate their time to help others without pay -helping people in need assisting at your child's school volunteering at a food bank or other charity, or encouraging newcomers to integrate. Volunteering is an excellent way to gain useful skills and develop friends and contacts.

    Protecting and enjoying our heritage and environment—every citizen has u role to play in avoiding waste and pollution while protecting Canada's natural, cultural and architectural heritage for future generations.

    Tiny microbes(微生物)are at the heart of a new agricultural technique to manage harmful greenhouse gas. Scientists have discovered how microbes can be used to turn carbon dioxide into soil-enriching limestone(石灰石), with the help of a type of tree that grows in tropical areas, such as West Africa.

    Researchers have found that when the Iroko tree is grown in dry, acidic soil and treated with a combination of natural fungi(霉菌)and other bacteria, not only does the tree grow well, it also produces the mineral limestone in the soil around its root.

    The Iroko tree makes a mineral by combining Ca from the earth with CO2 from the atmosphere. The bacteria then create the conditions under which this mineral turns into limestone. The discovery offers a new way to lock carbon into the soil, keeping it out of the atmosphere. In addition to storing carbon in the trees, leaves and in the form of limestone, the mineral in the soil makes it more suitable for agriculture.

    The discovery could lead to reforestation(重新造林)projects in tropical countries, and help reduce carbon dioxide in the atmosphere in the developing world. It has already been used in West Africa and is being tested in Bolivia, Haiti and India.

    The findings were made in a three-year project involving researchers from the Universities of Edinburgh, Granada, Lausanne and Delft University of Technology. The project examined several microbiological methods of locking CO2 as limestone, and the Iroko-bacteria way showed best results. Work was funded by the European Commission under the Future Emerging Technologies (FET) scheme.

    Dr Bryne Ngwenya of the University of Edinburgh's School of GeoSciences, who led the research, said: "By taking advantage of this natural limestone-producing process, we have a low-tech, safe, readily employed and easily operating way to lock carbon out of the atmosphere, while improving farming conditions in tropical countries?