C

    Measles(麻疹), which once killed 450 children each year and disabled even more, was nearly wiped out in the United States 14 years ago by the universal use of the MMR vaccine(疫苗). But the disease is making a comeback, caused by a growing anti-vaccine movement and misinformation that is spreading quickly. Already this year, 115 measles cases have been reported in the USA, compared with 189 for all of last year.

    The numbers might sound small, but they are the leading edge of a dangerous trend. When vaccination rates are very high, as they still are in the nation as a whole, everyone is protected. This is called “herd immunity”, which protects the people who get hurt easily, including those who can't be vaccinated for medical reasons, babies too young to get vaccinated and people on whom the vaccine doesn't work.

    But herd immunity works only when nearly the whole herd joins in. When some refuse vaccination and seek a free ride, immunity breaks down and everyone is in even bigger danger.

    That's exactly what is happening in small neighborhoods around the country from Orange County, California, where 22 measles cases were reported this month, to Brooklyn, N.Y., where a 17-year-old caused an outbreak last year.

    The resistance to vaccine has continued for decades, and it is driven by a real but very small risk. Those who refuse to take that risk selfishly make others suffer.

    Making things worse are state laws that make it too easy to opt out(决定不参加) of what are supposed to be required vaccines for all children entering kindergarten. Seventeen states allow parents to get an exemption（豁免), sometimes just by signing a paper saying they personally object to a vaccine.

    Now, several states are moving to tighten laws by adding new regulations for opting out. But no one does enough to limit exemptions.

    Parents ought to be able to opt out only for limited medical or religious reasons. But personal opinions? Not good enough. Everyone enjoys the life-saving benefits vaccines provide, but they'll exist only as long as everyone shares in the risks.

    Organic exercise is a good fit for people looking to train functionally. It is defined as exercise that is similar to the type of physical activity performed by ancient hunter-gatherer ancestors. Organic exercise is generally preformed in natural or outdoor settings. {#blank#}1{#/blank#} Organic exercise may include such activities as walking, jogging, swimming, hiking or rock climbing.

    When it comes to organic exercise, one of its most significant benefits is its limited reliance on equipment. {#blank#}2{#/blank#} Going for a jog, walking, or even hiking does not require tools, weights, or even hiking does not require tools, weights, or other products, and therefore, is fairly inexpensive.

    Since the types of activity emphasized in organic exercise programs are similar to those performed as part of daily life, they do not require extensive or long amounts of practice to obtain proficiency(精通). {#blank#}3{#/blank#} Therefore the type of activity recommended in an organic workout routine can be performed by beginning or advanced exercisers alike with relative ease.

    While the type of exercise recommended in an organic workout may be easy enough to perform, the intensity at which it is recommended can be too much for some individuals. {#blank#}4{#/blank#} Individuals who are new to exercise or suffer from a chronic health condition that limits their physical ability may find it difficult to perform exercise that is especially strenuous.

    {#blank#}5{#/blank#} Individuals who are new to exercise may want to talk with their health care provider before choosing this type of activity. In some cases, it may be better to start off with a more traditional workout and slowly transition to organic exercise than starting with this regimen(养生法)right off the bat.

A. Weigh both the benefits and drawbacks.

B. In fact, it can be done nearly anywhere, any time.

C. Therefore it requires very little helping equipment.

D. Choosing the right types of organic exercise is important.

E. Most adults already know how to hike, swim or dig, for example.

F. In fact, one of the biggest drawbacks is the emphasis on high-intensity exercise.

G. While organic exercise may be a good choice for some, it is right for all adults.

    When I was a baby, I entertained you and made you laugh. Whenever I was “bad”, you'd shake your finger at me and ask, “How could you?”--but then you'd give up, and roll me over for a belly scratch and I believed that life could not be any more perfect.

    My house-training was a long process, because you were terribly busy, but we worked on that together. We went for long walks, runs in the park and car rides. We stopped for ice cream. I took long naps in the sun waiting for you to come home at the end of the day.

    Gradually, you began spending more time at work and on your career, and more time searching for a human mate. Eventually, you fell in love. She, now your wife, is not a dog person, but I still welcomed her into our home. I was happy because you were happy. Then the human babies came along and I shared your excitement, I was fascinated by their pinkness, how they smelled, and I wanted to mother them too. Your wife was afraid I would bite them. But nevertheless, as they began to grow, I became their friend.

    Now, you have a new job in another city and you and they will be moving to an apartment that does not allow pets. You've made the right decision for your “family”, but there was a time when I was your only family.

    I was excited about the car ride until we arrived at the dog pound. It smelled of dogs and cats, of fear, of hopelessness. You filled out the paperwork and said, “I know you will find a good home for her.” They shrugged and gave you a pained look. The children were in tears as they waved me goodbye. And “How could you?” were the only three words that swept over my mind.

    Is it better to live with hope or without hope? At first, whenever anyone passed my pen (围栏), I rushed to the front, hoping it was you, that you had changed your mind and that this was all a bad dream.

    My beloved master, I will think of you and wait for you forever. I hope you receive more faithfulness from your family than you showed to me.

    Six months after a Chinese scientist was widely condemned for helping to make the world's first gene­edited babies, he remains out of public view, and new information suggests that others may be interested in undertaking the same kind of work outside the United States.

    A clinic in the United Arab Emirates city of Dubai emailed scientist He Jiankui to seek training in gene editing, Stanford University bioethicist Dr. William Hurlbut said ahead of a speech Tuesday at the World Science Festival in New York.

    Hurlbut, whose advice He often sought, said He told him that scientists from multiple countries and families with inherited health problems had messaged support and interest in altering the genes of embryos(胚胎)to prevent or treat disease. Hurlbut gave The Associated Press the email the Dubai clinic sent to He in December but decided to hide the clinic's name.

    "It reveals what eagerness there is out there to use this technology" and the need "for some sort of practical governance" of it, Hurlbut said.

    Jennifer Doudna, a University of California, Berkeley, co­inventor of the CRISPR gene­editing tool that He used, said that she also has heard of others who want to edit embryos.

    "I think they're entirely credible," she said of such reports. Doudna, who was also a speaker at the New York festival, said the field needs to focus on setting specific principles for how and when such work should proceed.

    "The technology is frankly just not ready for clinical use in human embryos," although research should continue, she said. Doudna is paid by the Howard Hughes Medical Institute, which also supports AP's Health and Science Department.

    Scientists and policy leaders have been debating how to set international standards or controls since He claimed in November that he had altered the genes of twin girls at conception(怀孕)to try to help them resist possible future infection with the AIDS virus.

    Editing embryos is outlawed in many countries because it risks damaging other genes, and the DNA changes can be passed to future generations. Many scientists have condemned He's work, and attention has fallen on other scientists who knew or strongly suspected what He was doing.

    We all long for friendship, but how to make a friend? "The best time to make a friend is before you need one." Joy Steven said. The following are some tips for you.

    People equal friends

    Friends usually begin with strangers. Getting in touch with other people is the first step to make a friend. Friends can't be made in empty air. Best friends take time to make.

    Friends understand friends

    Friends understand each other when talking. Many unpleasant personal quarrels can be avoided if you will take the time to understand others' feelings and points of view.

    Friends touch friends

    Touching is a warm from of communication between friends. When you see best friends communicating, you will notice them stand close together, touch each other comfortably and listen to each other. Sometimes a friendly touch is more powerful than words.

    Friends praise friends

    Praise is a powerful tool to make a friend. Honest praise can affect (影响) your friends' lives. So try to praise your friends, including your general ones.

    Friends can loyal (忠诚的) and trustworthy

    Trust and loyalty go hand in hand for friends. Friends can share secrets with you, because good friends never break confidence (信心) and are loyal forever.

    Taking your pulse during physical activity allows you to measure how hard you are exercising. You should exercise to stay within your target heart range.

    Increasing your heart rate is a key part of exercise but it is important that your heart rate is not too high or too low. If you are a beginner, you should also be able to breathe comfortably while exercising. This will ensure that you are exercising at a level that is safe and effective for your body.

    The chart below illustrates target heart rate ranges for exercise based on the maximal heart rate for selected ages. Here are the steps for using the chart: