In cities with rent control, the city government sets the maximum rent that a landlord (房东) can charge for an apartment. Supporters of rent control argue that it protects people who are living in apartment. Their rent cannot increase; therefore, they are not in danger of losing their homes. However, the critics say that after a long time, rent control may have negative effects. Landlords know that they cannot increase their profits. Therefore, they invest in other businesses where they can increase their profits. They do not invest in new buildings which would also be rent-controlled. As a result, new apartments are not built. Many people who need apartments cannot find any. According to the critics, the end result of rent control is a shortage of apartments in the city.

    Some experts argue that the minimum wage law can cause problems in the same way. The federal government sets the minimum that an employer must pay workers. The minimum helps people who generally look for unskilled, low-paying jobs. However, if the minimum is high, employers may hire fewer workers. They will replace workers with machinery. Therefore, other things being equal, the number of workers that employers want decreases. Thus, critics hold the opinion that an increase in the minimum wage may cause unemployment. Some poor people may find themselves without jobs instead of with jobs at the minimum wage.

    Supporters of the minimum wage say that it helps people keep their dignity. Because of the law, workers cannot sell their services for less than the minimum. Furthermore, employers cannot force workers to accept jobs at unfair wages.

    Economic theory predicts the results of economic decision, such as decisions about farm production, rent control, and the minimum wage. The predictions may be corrected only if “other things are equal”. Economists do not agree on some of the predictions. They also do not agree on the value of different decisions. Some economists support a particular decision while others criticize it. Economists do agree, however, that there are no simple answers to economic questions.

    James Cleveland Owens was the son of a farmer and grandson of black slaves. His family moved to Cleveland when he was 9. There a school teacher asked his name.

    “J.C.,” he replied. She thought he had said “Jesse”, so he had a new name.

    Owens ran his first race at age 13. After high school, he went to Ohio State University. He had to work part-time so as to pay for his education. As a second year student, in the Big Ten games in 1935, he set even more records than he would in the Olympic Games a year later.

    A week before the Big Ten meet, Ovens accidentally fell down a flight of stairs. His back hurt so much that he could not exercise all week, and he had to be helped in and out of the car that drove him to the meet. He refused to listen to the suggestions that he give up and said he would try, event by event. He did try, and the results are in the record book.

    The stage was set for Ovens victory at the Olympic Games in Berlin the next year, and his success would come to be regarded as not only athletic（体育运动的）but also political. Hitler did not congratulate any of the African American winners.

    “It was all right with me,” he said years later. “I didn't go to Berlin to shake hands with him, anyway.”

    Having returned from Berlin, he received no telephone call from the president of his own country, either. In fact, he was not honored（给予荣誉）by the United States until 1976, four year before his death.

    Ovens' Olympic victories made little difference to him. He earned his living by looking after a school playground, and accepted money to race against cars, trucks, motorcycles and dogs.

    “Sure, it bothered me,” he said later. “But at least it was an honest living. I had to eat.”

    In time, however, his gold medals changed his life. “They have kept me alive over the years,” he once said. “Time has stood still for me. That golden moment dies hard.”

    On Sunday 23 April, more than 30, 000 people participated in the 2017 London Marathon, running 26.2 miles (42.2 kilometers) around the city centre.

    The London Marathon has taken place every year since 1981. At the first one just6,225 people completed the course, and since then it has grown into one of the biggest sporting events in the world. It is one of the “World Marathon Majors”, which is a competition made up of six global marathon events. The overall male and female winners receive $ 1 million in prize money between them. There are eleven people who have run every London Marathon since it began—they call themselves the “Ever Presents”.

    This year, the winners of the London Marathon were surprisingly both from Kenya— Daniel Wanjiru, who finished in 2 hours and 5 minutes, and Mary Keitany, whose time was 2 hours and 17 minutes.

    However, most marathon runners are not professional athletes. They are amateurs who have trained for months to raise money for charity or just as a personal challenge. For example, Tom Harrison took three days just to reach the run's halfway point, as he is crawling the course on his hands and knees dressed as a gorilla(大猩猩), trying to raise money and attention for the charity “The Gorilla Organization”.

    Matthew Rees was another runner to encourage people, as he stopped just before the finish line to help David Wyeth run the last 200m. They did not know each other before, but Matthew saw that David was exhausted and possibly close to collapsing, and wanted to help him finish.

    Every year there are lots of touching stories like this from the London Marathon, and it is a huge achievement even to run the 26.2 miles!

    Pakistan should be everyone's tourist destination for 2018, but what if you already live there?

    Then perhaps you should consider visiting these five must- visit places for the new year.

Lake Saiful Muluk

    At an altitude of 3, 224m, surrounded by now mountains, the lake rewards those that make the three-hour uphill walk from Naran. You will find the pathway just above the free market, but there is a superior option to get a jeep and split the costs with some other tourists; expect to pay about 700 rupees, worth it to view this natural beauty.

Deosai National Park

As another high point in Pakistan, it has an average altitude of 4,114m — the Deosai Plains are one of the highest plateaus(高原 )in the world. If you make it to the park, you expect to find rich plants and wild animals. The breathtaking scenery on show at the plains is enough to make 2018 a memorable year.

Naltar Valley

Accessible via a 2.5—hour drive from Gilgit, well worth visiting. Covered with pine trees and other plants, it has a dreamlike feel about it. Various colors all year around make you fall in love.

Shangrila Resort

    Right in the north of Pakistan in the Central valley of Gilgit-Baltistan. Locals call this a paradise(乐园）,and that's what it feels like. No visit is complete without checking out the restaurant which is built in the structure of an aircraft.

Rama Meadow

    Doesn't feel like Pakistan at all, more like somewhere in Minnesota. Watch the sheep and cows feeding while clear water flows in streams from high in the mountains. Against Chongra's ice-covered peak, this little meadow is a piece art.

                                                      Four Wild Animal Species Were Endangered

    Maybe you can still see them at the zoo. But that doesn't mean they're doing alright in the wild.

    Tigers

    All six tiger species are endangered, with Suatran tigers and South China tigers at a seriously endangered status. The main reasons for their population decline are illegal hunting and destroyed habitats, as humans clear forests to gather timber and build roadways. Only about 3890 tigers presently live in the wild.

    Ground squirrels

    That's right, even squirrels are endangered, specifically the San Joaquin ground squirrel. Native to California, USA, these guys have been disappearing since 1979 on account of the construction and human developments going through their habitat. Their total population is unknown, but it could be anywhere between 124000 and 4130000.

    Giraffes

    The International Union for the Conservation of Nature recently put giraffes at a vulnerable status, the level just before endangered. The giraffe population has declined 40 percent in the last 30 years, primarily due to loss of habitat and illegal hunting. Some giraffes are killed just for their tails, which are considered status symbols in Africa.

    Asian elephants

    The main threat to Asian elephants, one of the most intelligent animals, is their shrinking habitat. As the human population grows, people invade their land to build roads and railway tracks. Elephants in Myanmar are at an especially high risk for being captured and traded or used illegally in the tourist industry. Fewer than 50000 are left on the entire continent.

    Scientists think that growing garden grass could be the secret to solving our energy needs, and we may soon be able to replace our gasoline with "grassoline".

    The team, including experts from Cardiff University in Wales, has shown that hydrogen can be taken from grass in useful amounts with the help of sunlight and a cheap catalyst(催化剂) —something that speeds up a chemical reaction without being used up.

    It is the first time that this has been shown and it could lead to a sustainable(可持续的) way of making hydrogen, reported Asian News International. This could be an important kind of renewable energy because it is high in energy and it does not give out harmful gases when it is burned.

    Study co-author Michael Bowker said, "This is really a green source of energy. Hydrogen is seen as an important future energy carrier as the world moves from fossil fuels to renewable energy, and our research has shown that even garden grass could be a good way of getting it."

    Cellulose(纤维素), which is a key part of plants and the biopolymer(生物聚合物) found in the largest numbers on the earth, could be a great source of hydrogen.

In its study, the team looked at the possibility of getting hydrogen from cellulose using sunlight and a simple catalyst.

    This is called photocatalysis(光催化作用) and in it, the sunlight starts the catalyst, which then makes cellulose and water into hydrogen. The researchers studied the effectiveness of three metal-based catalysts, of which nickel(镍) especially interested the researchers, as it is a much more common metal than gold and palladium(钯) and it saves more money.

    According to Bowker, producing hydrogen from cellulose using photocatalysis has not been studied in detail. The team's research shows that large amounts of hydrogen can be produced using this method with the help of a bit of sunlight and a cheap catalyst.

    The study shows that it is effective to use real grass taken from a garden. "This is important as it avoids the need to separate and clean up cellulose, which can be both difficult and costly," said Bowker.