Traveling is a very good activity. When you are fed up with your work and are allowed to take a holiday, you can go to the beautiful spots to enjoy the beauty of nature and the special character of other cities. You can breathe fresh air, visit some places of interest, meet different people and make friends with them. Then you will feel fully relaxed and you will have the energy to undertake the new tasks waiting for you.

    But sometimes, traveling is not an enjoyable thing. For example, when the bus or car you take has a bad accident, you may be trapped in it and waste your time. What's more, the weather can be changeable. If you are climbing a mountain, it may rain suddenly. You may be caught in the rain and may catch a cold. The worst thing is that you may have your money stolen and you may have an injury. All these are terrible things that can happen to a tourist.

    Therefore, before going on a trip, you must prepare yourself carefully. Firstly, you must have clear information about the weather. Secondly, you should choose a good companion so that you can help each other. Thirdly, you must be careful everywhere and try to avoid accidents. If you do these, you can enjoy your travels better and reduce unnecessary trouble.

    Of all nature's disasters, forest fires are often considered the most frightening. Moving at lightning speed, huge walls of flames can burn acres of land in just a few minutes. And although technology, including the use of fire-retardant chemicals, has greatly helped the fight against forest fires, they still do great damage.

    According to the National Interagency Fire Center, the fire season last year was the worst on record in terms of the number of fires and acres burned. There were 96. 385 fires and 9.873429 acres affected by fire in a year that was 125% more destructive(毁灭性的) than the10-year average. These fires cost the federal government $1.5 billion to fight, and this figure does not include the money spent by local and state governments as part of the effort.

    Fires in the southern states represented half of the national total last year with Texas, Oklahoma and Arkansas being home to a usually high amount of activity. Wildfire has also taken place in Western states such as California, Colorado and Alaska throughout the past 10 years.

    It is said that two-thirds of forest fires are started accidentally by people. Almost one quarter are purposely set, while lighting causes 10%.

    Forest fires can have advantageous effects. Charcoal(木炭) enriches soil and some plant species(种类) grow well after fire. The cones of the jack pine tree, for example, will not spread their seeds unless there is heat. Douglas fir trees grow best in open sunlight areas after fire.

    Imagine walking through an ancient city, then climbing a gate tower to take in a wonderful view of the city and its more than 600-year-old walls. You can hear the city's heartbeat in the air. This is the Ancient City of Pingyao in Shanxi Province, a place that should definitely be on your travel route if you enjoy history or ancient architecture since its origins can be traced back to more than 2,700 years ago.

    Located in the center of Shanxi Province, Pingyao is the hometown of Jin merchants, a group of merchants who actively dominated (支配) a booming commodity market throughout China for more than 500 years, especially during the Ming and Qing dynasties. After the founding of the People's Republic of China in 1949, the city's agriculture and manufacturing industries developed rapidly. Following China's reform and opening-up in the 1980s, Pingyao struggled with the transition from a managed economy to the current market-oriented economy. During this time, the city government sought out new ways to break through this economic bottleneck.

    Finally in the winter of 1997, opportunity came knocking. Through the efforts of the city government, Pingyao earned its place on the UNESCO World Heritage list, which caused the entire world to take notice of the city.

    Since the city's fame has risen, locals in Pingyao have deepened their understanding of the conservation efforts preserving the historical relics in their hometown. Meanwhile the city administration has continued to upgrade itself through a strategy that follows the pillars of “conservation, entrepreneurship, development and protection.”

    Currently, the city is focused on establishing a sustainable industry that will enable it to continue to grow while also protecting its relics and introducing them to the world.

    Since English biologist Charles Darwin published On the Origin of Species in 1859, scientists have vastly improved their knowledge of natural history. However, a lot of information is still of the speculation, and scientists can still only make educated guesses at certain things.

    One subject that they guess about is why some 400 million years ago, animals in the sea developed limbs (肢) that allowed them to move onto and live on land.

    Recently, an idea that occurred to the US paleontologist (古生物学家) Alfred Romer a century ago became a hot topic once again.

    Homer thought that tidal (潮汐的) pools might have led to fish gaining limbs. Sea animals would have been forced into these pools by strong tides. Then, they would have been made either to adapt to their new environment close to land or die. The fittest among them grew to accomplish the transition (过渡) from sea to land.

    Romer called these earliest four-footed animals “tetrapods”. Science has always thought that this was a credible theory, but only recently has there been strong enough evidence to support it.

    Hannah Byrne is an oceanographer (海洋学家) at Uppsala University in Sweden. She announced at the 2018 Ocean Sciences Meeting in Oregon, US, that by using computer software, her team had managed to link Homer's theory to places where fossil deposits (沉积物) of the earliest tetrapods were found.

    According to the magazine Science, in 2014, Steven Balbus, a scientist at the University of Oxford in the UK, calculated that 400 million years ago, when the move from land to sea was achieved, tides were stronger than they are today. This is because the planet was 10 percent closer to the moon than it is now.

    The creatures stranded in the pools would have been under the pressure of “survival of the fittest”, explained Mattias Green, an ocean scientist at the UK's University of Bangor. As he told Science, “After a few days in these pools, you become food or you run out of food... the fish that had large limbs had an advantage because they could flip (翻转) themselves back in the water.”

    As is often the case, however, there are others who find the theory less convincing. Cambridge University's paleontologist Jennifer Clark, speaking to Nature magazine, seemed unconvinced. “It's only one of many ideas for the origin of land-based tetrapods, any or all of which may have been a part of the answer,” she said.

    Many foreign students report feeling lonely or unwelcome in Australia. Those feelings are among the reasons why Australia is taking a close look at its international education industry. But wherever international students go, making friends may not always be easy. Elisabeth Gareis of Baruch College in New York surveyed 454 international students. They were attending four-year colleges and graduate schools in the American South and Northeast.

    Students from English-speaking countries and from northern and central Europe were more likely to be happy with their friendships. But 38% of the international students said they had no close friends in the United States. And half of the students from East Asia said they were unhappy with the number of American friends they had. Thirty percent said they wished their friendships could be deeper and more meaningful.

    Professor Gareis says, “Students from East Asia have cultures that are different on many levels from the culture in the United States. There are also language problems, and maybe some social skills, such as small talks, which are possibly not as important in their native countries, where it's not as important to start friendships with small talks. Many East Asian students blamed themselves for their limited friendships with Americans, for not speaking the language well enough and for not knowing the culture well enough.”

    VOA's Students Union blogger Jessica Stahl did her own survey to find out how American students and foreign students relate to each other. More than 100 students, about half of them American, answered her online questions. Half of the international students and 60 % of the Americans said they related as well or better to the other group than to their own group.

    Professor Gareis says, “International students who make friends with host nationals are, overall, more satisfied with their stay in the host country. They have better language skills, better academic performance and better attitudes toward the host country.”