Do you drink water that's been left sitting out overnight or even for another day? Have you noticed it tastes different?

    Tap water that has been left to sit out slowly begins to acquire(获得) off taste. Many people think that this is because of microorganisms. But that's not what makes old water taste not fresh. For that we can thank carbon dioxide. After about 12 hours, tap water starts to go flat as carbon dioxide in the air starts to mix with the water in the glass, lowering its pH and giving it an off taste. But it's most likely safe to drink.

    However, back to those microorganisms. If you use a dirty glass day after day, there is more of a chance of bacteria making themselves known; a risk that increases if you share the glass with another mouth as well. But assuming(假设) you use a fresh glass every few days, you probably won't have a problem unless the glass has been touched by dirty fingers, and especially if those dirty fingers went unwashed after using the bathroom.

    As for plastic water bottles that have been left out in the sun or in the car, step away from the bottle, warns Dr. Kellogg Schwab, director of the Johns Hopkins University Water Institute. "A chemical called biphenyl-A, or BPA, along with other things used to make plastic can leach(过滤) into your water if the bottle heats up or sits in the sun," he explains. BPA, as you probably know, has been linked to everything from heart disease to cancer. Schwab also adds that plastic used for commercial bottled water isn't meant to be washed or refilled, so use only one time and recycle. Or don't buy them at all; use refillable water bottles instead.

    Hobbs was an orphan. He worked in a factory and every day he got a little money. Hard work made him thin and weak.  He wanted to borrow a lot of money to learn to paint pictures, but he did not think he could pay off the debts.

    One day a lawyer said to him, “One thousand dollars, and here is the money.” As Hobbs took the package of notes, he was very dumbfounded. He didn't know where the money came from and how to spend it. He said to himself, “I could go to find a hotel and live like a rich man for a few days；or I give up my work in the factory and do what I'd like to do: painting pictures. I could do that for a few weeks, but what would I do after that? I should have lost my place in the factory and have no money to live on. If it were a little less money, I would buy a new coat, or a radio, or give a dinner to my friends. If it were more, I could give up the work and pay for painting pictures. But it's too much for one and too little for the other.”

    “Here is the reading of your uncle's will,” said the lawyer, “telling what is to be done with this money after his death. I must ask you to remember one point. Your uncle has said you must bring me a paper showing exactly what you did with his money, as soon as you have spent it.”

    “Yes I see. I'll do that,” said the young man.

    Everything has a name. All people, places and things have names. For example, Jenny is the name of a student from England. England is the name of her country. Cities and towns have names, too. Schools and office building also have names. All things have names. Names are important.

    Names are different all over the world. In Jenny's class, Jenny must learn the names of students from all over the world. This is very difficult because the names are different.

    In the USA, most people have a first name, a middle name, and a last name. Parents choose the first and middle names for their baby. There are names for boys and names for girls. For example, John, Peter, Tom and Mike are all names for boys. Elizabeth, Betty, Susan, and Mary are all names for girls. The last name is the family name. Usually it is the father's family name. In a family, the mother, the father, and the children usually have the same last name.

    Names are different all over the world. They can be long or short, but they are always very important.

    Having a job is great, I have learned. It means I can afford things such as a place to live and daily meals. And with an above-average job, I can afford a car and occasional overseas vacations.

    However, I also understand how difficult it is to have a below-average job, having had many of them before. It's frankly pretty awful. Owning a car was out of the question – I could barely afford to ride the subway.

    So, I decided to go to university and get a degree.

    Later, I emailed my details to every company and government institution with an online careers page. I even printed my resume and handed it out in what seemed like hundreds of office buildings.

    One summer during university, my cousin and I helped out at my uncle's business, fixing roofs, although the only thing I got out of that was back problems.

    That same year, I got a job at a plumbing(管道工程) company, which I was terrible at. It was no surprise when I was asked to leave that job after only four days.

    A lot of people today believe the problem of unemployment in my generation is our fault. Some accuse us of being lazy or feeling too entitled(有资格的). At the same time, some people accuse members of my generation of having a sense of “specialness” that has led us to believe we can all be astronauts, movie stars or singers if we put our minds to it. Also, a few of them think that we would all be happily employed if we would only learn trades or become software engineers, because those people make the most money.

    I realize that not everyone can go into space, star in Hollywood movies or fill stadiums with fans, however. I also think not everyone can make a good electrician or design advanced computer software – I know I can't. Everyone is good at something, but no one is good at everything. It took me hundreds of rejection emails to realize that I had to focus on finding a job where I could actually be successful.

    And now, I finally have that job. All it took was several years of desperation, failure and an honest assessment(评估) of my personal value in the job market.

    It's not the best start, but it's not bad for a start too.

    According to a recent study, a new genetically modified rice can prevent infections of HIV, the virus responsible for the disease AIDS.

    The study reports the newly-developed rice produces proteins that attach directly to the HIV virus. This process prevents the virus from mixing with human cells. The scientists say it can remove the effect of the virus and block its spreading.

    The Joint United Nations Program on HIV/AIDS reports that worldwide, nearly 37 million people were living with HIV in 2017. The organization says the largest number of those are in developing countries. Nearly two-thirds of HIV cases are in Africa. Now there is no cure for HIV/AIDS though there have been developments in oral drug treatments to slow the progression of the disease.

    The new study predicts the rice-based method will lead to long-term use of the anti-HIV treatment across the developing world. Researchers said the "groundbreaking" discovery is "realistically the only way" that anti-HIV combination treatments can be produced at a cost low enough for the developing world.

    They say the easiest and most cost-effective way to use the rice will be to make it into a cream to be put on the skin. The HIV-fighting proteins can then enter the body through the skin. People all over the world could grow the rice and make the cream themselves. This would prevent the cost and travel required for many patients to receive treatments and medicine.

    The process of changing the genetic structure of food crops has been debated for some time. Critics of genetically engineered crops believe they can harm people. The scientific team says further testing is needed to ensure that the genetic engineering process does not produce any additional chemicals that could be dangerous to people.

    Have you ever been to London? Here is some hotel information for you.