Almost every night for more than 10 years, Kirk Alexander, 48, ordered a late dinner from his local restaurant Domino's Pizza. But for the past two weeks, he hasn't called for even once.

    “A few of my staff mentioned that we hadn't seen his order in a while. Then I found that it had been 12 days since he last ordered, which is not like him,” Domino's general manager Sarah Fuller said, feeling she could no longer ignore Kirk's recent absence.

    Sarah has known Kirk since 2009, when she started working at the Domino's Pizza as a deliver driver and often made the short trip to Kirk's home about six minutes away. She knew Kirk worked from home, and neighbors said he seldom left. She also knew that he had some health problems in the past. Something, Sarah worried, was wrong.

    Around 1 a.m. on May 8, Sarah sent delivery driver Sean Hamblen to visit Kirk's home. Sean arrived at Kirk's home and knocked on the front door several times. There was no answer. He later noticed that the lights and the TV in the home were on. When he called Kirk's phone, it went straight to voice mail.

    Sean drove back to the restaurant to tell Sarah and they decided to call 911. Soon, officers arrived at Kirk's home. So did Sarah and Sean. They heard a man calling for help from inside. Officers broke down the door and found Kirk on the floor in need of medical attention at once after suffering from a heart attack. One day later, they might have been too late.

    So is keeping an eye on regular customers part of Domino's business plan? Not really. “Kirk is part of our family here and we feel like we need to do something.” Sarah said.

    Scientists are trying to save Puerto Rico's endangered Amazon parrots after Hurricane Maria destroyed the birds' habitats and food sources(来源).

    El Yunque is a large national forest on the eastern part of Puerto Rico. Just two of the 56 wild parrots that once lived there survived Maria, the Category-4 storm that struck Puerto Rico in September 2017. Scientists report other forests have seen great drops in parrot populations as well.

    In the 1800s, there were more than a million of the bright green parrots living in the wild in Puerto Rico. By the 1970s, the number was down to just 13 birds after years of forest clearing.

    A special program was started in 1972 to help increase the parrot population, which led to the creation of three breeding(繁殖) centers. Just weeks before Hurricane Maria hit, scientists counted 56 wild parrots at El Yunque. That was the highest number in the program's history. Scientists say that even though several parrots have been born in captivity(笼养) and in the wild since Maria, the species is still in danger.

The Puerto Rican Amazon is the island's only remaining native parrot. More than 460 of the birds are kept inside the breeding centers at El Yunque and the Rio Abajo forest. Scientists have not released(释放) any of the birds since Hurricane Maria. A third breeding center, in a forest in the western area of Maricao, has not been in operation since the storm.

    Scientists are considering whether to catch some of the remaining wild parrots and put them in the same cage as the birds that are set to be released. This way, the captive birds can learn from the wild birds how to survive in the forests. Another consideration is to release some captive parrots in Maricao, which was not as heavily damaged by Maria.

    Joey was born in 1990 in Connecticut and now lives in North Carolina in the United States. When Joey was six, he started racing small cars in competitions. He began to win many races, but they weren't big races. His parents decided to move to Atlanta, Georgia, so Joey could compete in bigger and better competitions. When he was 12, he set a record by winning 14 races in a row at the Atlanta Motor Speedway. He continued to win many races, and finally began racing with regular-sized (正常大小的) race cars.

    When Joey was 15 years old, he met the race car driver Mark Martin. Martin is a famous NASCAR driver. NASCAR is the National Association for Stock Car Auto Racing, and it is the biggest and most popular car-racing organization in the United States. Martin was interested in Joey and thought he was “the real deal.” He said, “I am sure that he can be one of the greatest that ever raced in NASCAR. There's no doubt in my mind.”

    Martin was right. Joey started as a NASCAR driver in 2007. NASCAR has many races, and at first, Joey was only able to compete in smaller races because of his age. In his first NASCAR season, he won a championship (冠军). In 2008, he was able to compete in bigger NASCAR competitions. He competed in one of the top NASCAR racing series called the Nationwide Series, and at 18, he became the youngest winner in Nationwide Series history.

    In 2009, he became the youngest winner in another top NASCAR racing series called the Sprint Cup Series, and he also won the Nationwide Series for the fifth time. To be one of the best drivers in the history of racing, Joey has to win many more races. But at 19, he's off to a good start.

    Humans and many other mammals have unusually efficient internal temperature regulating systems that automatically maintain stable core body temperatures in cold winters and warm summers. In addition, people have developed cultural patterns and technologies that help them adjust to extremes of temperature and humidity (湿度).

    In very cold climates, there is a constant danger of developing hypothermia, which is a life-threatening drop in core body temperature to below normal levels. The normal temperature for humans is about 37.0℃. However, differences in persons and even the time of day can cause it to be as much as 6℃ higher or lower in healthy individuals. It is also normal for core body temperature to be lower in elderly people. Hypothermia begins to occur when the core body temperature drops to 34.4℃. Below 29.4℃, the body cools more rapidly because its natural temperature regulating system usually fails. The rapid decline in core body temperature is likely to result in death. However, there have been rare cases in which people have been saved after their temperatures had dropped to 13.9-15.6℃. This happened in 1999 to a Swedish woman who was trapped under an ice sheet in freezing water for 80 minutes. She was found unconscious, not breathing, and her heart had stopped beating, yet she was eventually saved despite the fact that her temperature had dropped to 13.7℃.

    In extremely hot climates or as a result of uncontrollable infections, core body temperatures can rise to equally dangerous levels. This is hyperthermia. Life-threatening hyperthermia typically starts in humans when their temperatures rise to 40.6-41.7℃. Only a few days at this extraordinarily high temperature level is likely to result in the worsening of internal organs and death.

    Qingming Festival, which falls on April 5 this year, is known as Tomb-Sweeping Day. The festival always appears about the beginning of April when spring has come. Not only is it a period for commemorating the dead, it is also a time for people to go out and enjoy nature.Where is the best place to go during the festival? Here are 3 popular tourist attractions.

    Jiuzhaigou Valley Scenic and Historic Interest Area

    In the spring, the sight of the Jiuzhaigou Valley is refreshing and touching. The ice and snow begin to melt, water and streams begin to flow and mountain flowers blossom. The air is filled with the fragrance of spring. The soft and lazy spring sun kisses the surface of the lake and new growth.

    Huanghuacheng Great Wall

    Huanghuacheng is the only lakeside part of the Great Wall in Beijing. It is one of the most popular destinations for a Great Wall hiking tour. It is a hit because of the "train for spring", namely a train that travels through fields full of cherry blossoms.It is extremely romantic to take this train in spring with someone you love.

    Mount Huangshan

    Of all the notable mountains in China, Mount Huangshan is probably the most famous and is found in the southern part of East China's Anhui province. It is known for its breathtaking natural scenery.In the spring, Mount Huangshan is fresh, tender and full of wild flowers, and the sound of birdsong also is pleasant in the quietness