The Leaning Tower of Pisa was straight like a pole when the construction began in 1173. It started to shift direction soon after construction because of poor foundation in addition to the loose layer of subsoil(底土). At the beginning, it leaned to the southeast before the shaky foundation started to shift leaning towards the southwest. After the period of structural strengthening at the beginning of the 21^st century, now the Leaning Tower of Pisa leans at an angle of 3.97 degrees.

    In 1178, the shift in direction was observed for the first time when the construction had progressed further to the third floor. The tower was heavy for the three-meter foundation that was built on a weak area of land.

    For compensating(补偿) the leaning position, the builders started to construct the upper floors with one side higher than the other one. This caused the tower to lean in the other direction. This unusual structure led to the tower being actually curved. In spite of these efforts, the tower kept on leaning.

    The government of Italy started to plan prevention of the complete collapse of the tower in 1964. However, a request was put forward by the authorities to keep the leaning position because of the tourism industry of the region.

    After nearly two decades of careful planning by engineers, historians and mathematicians, the stabilization efforts for the Leaning Tower of Pisa started in 1990. The tower was closed for the general public and the people living nearby moved away. For reducing the total weight of the tower, its seven bells which represented the seven musical notes were removed. The tower was reopened for the general public on December 15, 2001.

    In May 2008, after removing another 70 metric tons of earth, the engineers announced that the tower had been finally stabilized and it would remain stable for at least 200 years.

    An organization, Eye Care 4 Kids, is bringing much-needed eye care to poor kids. It provides free eye examinations for kids from poor families. Founded by Joseph Carbone in 2001, the organization has helped around 100,000 children in Utah and Nevada.

    Now, Cecil Swyers, a biomedical(生物医学的) engineer who was once a poor child himself, is bringing the charity's(慈善) services to poor students in Arizona, so that vision impairment(视力受损) doesn't stand in the way of their education.

    “Eye Care 4 Kids is bringing eye care and glasses to families that wouldn't have the means to pay for them,” said Mario Ventura from Isaac Elementary School District, the first school district in Arizona to receive its services.

    Good vision is important to a child's learning experience. According to a study, up to 80 percent of learning happens through sight for children between 6 and 18 years old. Without proper eye care, it's difficult for students to learn better and succeed.

    Swyers is hoping that by bringing the organization to Arizona he'll help a lot more students. He teamed up with two other organizations to get doctors to volunteer their time with the group. Using an Eye Care 4 Kids mobile clinic, Swyers visited Alta E. Butler Elementary School and has already helped 40 students.

    The school was grateful to receive the eye care, especially since the services came to them. “It's great for us,” said Assistant Principal Cindy Alonso.

    Swyers is hoping to bring Eye Care 4 Kids' services to other schools in the state. He said that hopefully his work will have a positive effect on students' futures. “If we can help students while they're young, we can make a difference in their futures,” he said.

    Six years ago at the age of 35,I suddenly decided I wanted to learn the cello（大提琴）.Straight away I rented an instrument and appeared before Wendell Margrave,professor of musical instruction.

    "You can be as good as you want to be,"Margrave said rather mysteriously.On a piece of paper he drew the notes E and F.He showed me where to put my fingers on the neck of the cello and how to draw the bow.Then he entered my name in his book: 10 am,Tuesday.Tuesday followed Tuesday,and soon it was spring.

     Thus began my voyage out of ignorance and into the dream.E-F,E-F,we played together—and moved on to G.It was a happy time.I was again becoming something new,and no longer trapped as the same person.Surely the most terrible recognition of middle life is that we are past changing.We do what we can already do.The cello was something I couldn't do.Yet each Tuesday this became less and less true.Riding home on the bus one snowy night and learning the score of Mozart's C-Major Quintet(莫扎特的C大调五重奏),I felt the page burst into music in my hands.I could by then more or less read a score,and was humming（哼唱）the cello line,when suddenly all five parts came together harmonically（和谐地） in my head.The fellow sitting opposite stared.I met his glance with tears,actually hearing the music in my head for the first time.Could he hear it too, perhaps?No,he got off at the next stop.

    As the years slipped by,my daughter grew up,playing the piano well.My goal was that she and I would one day perform together.I also wanted to perform in public with and for my peers,and to be secretly envied.I continued to play,to perform,but it is not the same. Before, when I heard a cello,it was all beauty and light.Now,as the TV camera gets close to Rostropovich's face,I recognize that his smile shows his incredible determination.Even for him,the cello is a difficult instrument that doesn't respect your ambitions.I picked up my cello and practiced.As good as I wanted to be,I am as good as I'm going to get.It is good enough.

    There are many places to go on safari in Africa, but riding a horse through the flooded waters of Botswana's Okavango Delta must rank as one of the world's most exciting wildlife journeys.

    Several safari camps operate as the base for this adventure, providing unique rides twice a day to explore deep into the delta. The camps have excellent horses, professional guides and lots of support workers. They have a reputation for providing a great riding experience.

    The morning ride, when the guides take you to beautiful, shallow lakes full of water lilies, tends to be more active. It is unlike any other riding experience. With rainbows forming in the splashing water around you and the sound of huge drops of water bouncing off your body and face. It is truly exciting. You are very likely to come across large wild animals, too. On horseback it is possible to get quite close to elephants, giraffes and many other animals. The sense of excitement and tension levels rise suddenly though, as does your heart rate, as you move closer to them.

    In the evening, rides are usually at a more relaxed and unhurried pace. With golden light streaming across the grassy delta and the animals coming out to eat and drink. Sedate though they are, rides at this time of day are still very impressive. As the sun's rays pass through the dust kicked up by the horses, the romance of Africa comes to life.

    Back at the camp you can kick off your boots and enjoy excellent food and wine. Looking back on your day, you will find it hard to deny that a horseback Safari is as close as you will ever come to answering the call of the wild.

    Throughout much of human history, man has been the measure of many, if not all, things. Lengths were divided up into feet and smaller units from the human hand. Other measures were equally characteristic. Mediterranean traders for centuries used the weight of grains of wheat to define (定义) their units of mass. The Romans used libra, forerunner of the pound, by referring to the weight of a carob (角豆树) seed.

    The sizes of similarly named units could also differ. The king's foot, used in France for nearly

    1,000 years after its introduction by Charlemagne in around 790 AD, was, at 32.5cm,around a centimeter shorter than the Belgic foot, used in England until 1300.Greek,Egyptian and Babylonian versions of water in a fixed container varied from one another by a few kilos, Nor was there agreement on such things within countries. In France, where there was no unified (统一的) measurement system at the national level, the situation was particularly terrible. The lieue (former measure of distance), for example, varied from just over 3 km in the north to nearly 6 km in the south.

    Although John Wilkins, an Englishman, first put forward a decimal system (十进制) of measurement in 1668,it was the French who in 1799 made it law. The Système International d'Unités (SI, or the metric system, as it is better known) developed from it and became the official measurement in all countries except Myanmar, Liberia and the United States. Now the International Bureau of Weights and Measures in Paris is set to give the metric system its biggest shake-up yet.

    At a meeting in Versailles, France, on November 16th,2018,the world's measurement bodies are almost certain to approve a decision that will mean four out of the seven base SI units, including the kilogram, will follow the other three, including the metre, in being redefined in terms of the values of physical constants (物理常数).Each of the chosen constants has been measured incredibly precisely, which would mean that from May 20^th 2019 the constants will themselves be fixed at their current values for ever. Any laboratory in the world will then be able to measure, for example, the mass of an object as precisely as the accuracy of their equipment will allow.

    "What kind of rubbish are you?" This question might normally cause anger, but in Shanghai it has become a special "greeting" among people over the past week. On July 1st, the city introduced strict trash-sorting regulations (条例)that are required to follow and expected to be used as a model for our country. Residents must divide their waste into four separate categories and toss (投放)it into specific public dustbins. They must do so at specified times, when monitors are present to ensure correct trash-tossing and to ask the nature of one's rubbish. Individuals who fail to follow the regulations face the possibility of fines and worse. They could be punished with fines of up to 200 yuan ( $ 29). For those who repeat to go against them, the government can add black marks to their credit records, making it harder for them to get bank loans or even buy train tickets.

    Shanghai government is responding to an obvious environmental problem. It generates 9 million tons of garbage a year, more than London's annual output, which is rising quickly. But like other cities in China, it lacks a recycling system. Instead, it has relied on trash pickers to sift (筛选)through the waste, picking out whatever can be reused. This has limits. As people get wealthier, fewer of them want to do such dirty work. The waste, meanwhile, just keeps piling up.

    Many residents appear to support the idea of recycling in general but are annoyed by the details. Rubbish must be divided according to whether it is food, recyclable, dry or harmful, the distinctions among which can be confusing, though there are apps to help work it out. Some have complained about the rules concerning food waste. They must put it straight in the required public bins, forcing them to tear open plastic bags and toss it by hand. What they complain most is the short periods for dropping trash, typically a couple of hours, morning and evening. Along with the monitors at the bins, this means that people go at around the same time and can keep an eye on what is being thrown out no one wants to look bad.