Native woodlands can resist the spread of invasive species by blocking daylight reaching the forest floor, researchers have suggested.
The team, consisting of researchers from US universities, decided to focus its attention on common buckthorn(沙棘), which is all invasive species in North America. It out-competes native plants and degrades soils and forests, doing harm to humans and other wildlife. In order to create environments that resist invasion by buckthorn, and thus avoid those costs, it was necessary to understand which forest characteristics offered the greatest influence on the success or failure of buckthorn plants becoming established.
In their experiment, the team grew buckthorn under a variety of different levels of shade and measured the light available to the buckthorn. These included one made up from deciduous species, such as birch, another from evergreen species, such as pine, and another from a mixture of both species.
Dr. Schuster observed: “Results showed that forests that are able to block out 96% of incoming light in the spring or autumn can successfully resist buckthorn invasion.” He added that, in general, evergreen species were much more capable of creating this level of shade compared with deciduous species.
“We anticipated that buckthorn would fail in areas with extremely low light levels, since having some light is necessary for most plants to live,” he said. Yet the team were surprised by how much the buckthorn depended upon light availability in spring or autumn.
He added that if forest managers were seeking to improve the long-term resistance of their forests to buckthorn invasions, then it might be necessary to introduce species that helped reduce the amount of light reaching the forest floor, such as evergreens.
But this approach was not risk-free, warned Dr. Schuster. He added: “If we change forests to get rid of buckthorn, we may push out some desirable native species at the same time. So, the question becomes whether we can select plant communities both to have the species we want and to produce ample shade in spring and autumn to keep buckthorn out.”
1.This experiment was carried out to study ________.
A.why soil conditions matter to plants B.how to help native plants grow better and faster
C.the impact invasive species have on humans D.the factors influencing the growth of buckthorn
2.What kinds of trees were chosen for the experiment?
A.Trees providing different amounts of shade. B.Trees growing and declining at different rates.
C.Trees of different heights. D.Trees of different origins.
3.What does Dr. Schuster imply in the last paragraph?
A.We must get rid of buckthorn whatever the cost.
B.Keeping native species ought to be the top priority.
C.We should be careful about selecting species of plants.
D.Communities need to work together to fight the alien plants.
4.You may likely find this article in a ________.
A.psychological and behavioural paper B.travel guide
C.nature and environment journal D.fashion magazine
Two motorists saved the life of a good man who had moments earlier helped them.
Victor, 61, stopped his pickup along an interstate highway in western Wisconsin to help two stranded women change a flat tire. Minutes later, his life was in their hands.
Sara Berg, and her cousin, Lisa, were headed home Saturday night on Interstate 94 when they heard an awful noise. They were somewhere between Menomonie and Eau Claire when they pulled to the side of the road with a flat tire-something neither knew how to fix. Ann showed up and asked whether they needed help. “We were so grateful.” Berg said. “Nowadays, nobody ever really stops to offer their help. It's kind of scary sometimes, because you really don't know what you're getting into.”
Victor is the type of person who gives you 100 percent and worries about himself later. When Victor finished, Berg thanked him and they shook hands. Berg recalled Victor's farewell words to her: “Someone up above always puts me in the right place at the right time.”
And then they parted. Victor and his wife puffed back onto the interstate. Seconds later, Berg followed. Less than a quarter mile down the road, Berg noticed Victor's red truck pulled over. She passed it and then pulled over herself, figuring the couple may have forgotten something. No sooner had she gotten out of her car when she saw Victor's wife waving anxiously at passing motorists. She called out to Berg that her husband was having a heart attack. Berg, a certified nursing assistant trained in CPR, jumped into the truck. Victor had no pulse and wasn't breathing. Berg began chest compressions. Lisa called 911. Emergency personnel arrived in about five minutes, “but it always feels like forever at a time like that,” Berg said.
“It was a nice twist of fate.” said the doctor who is treating Victor at the Eau Claire hospital.
“We know for sure that the CPR the woman did increased his chances for survival.”
Ann, who was also part of her husband's good luck when she guided their vehicle to the shoulder during his heart attack, is grateful.
1.The underlined word “stranded” in Paragraph 2 means ________.
A.trapped B.exhausted
C.frightened D.threatened
2.What do Victor's farewell words mean?
A.Victor and Berg share a common religious belief.
B.Victor feels it his mission to lend a helping hand.
C.Victor happens to be expert in changing flat tires.
D.Victor expects Berg to do him a favor in return.
3.What happened to Victor shortly after they parted?
A.His pickup broke down and had to stop on the shoulder.
B.His heart was badly injured due to a terrible accident.
C.He pulled over to collect something left in Berg's car.
D.He suffered a sudden heart attack and lost his consciousness.
4.Which can be the best title?
A.A Twist of Fate B.A Lucky Man
C.An Adventurous Journey D.An Instant Rescue
Feb. 29, or Leap Day, arrives on your calendar once every four years—and 2020 is one of them. The reason there are 366 days every four years instead of the standard 365 is that the calendar doesn't precisely line up since the Earth orbits the sun in approximately 365 days and 6 hours. Hence, every 4 years a leap day, February 29th, has to be added to correct for the difference.
It's not a federally recognized holiday, but Leap Day is a special occasion, so retailers typically offer many sales, deals and discounts. From food to travel deals, here are 29 Leap Day 2020 discounts.
●Hard Rock Café: Customers with a Leap Day birthday receive a free entrée from the restaurant's Leaplings Eat Free menu with a valid photo ID.
●Dog Hans: Enjoy a free upgrade from a single to a double burger on Feb. 29, which will save you $2.49.
●Legal Sea Foods: Get two 1-pound lobsters and two sides at any of the East Coast eatery's 30 non-airport locations for $29(over a $50 value) on Feb. 29.
●Big Frog Custom T-Shirts ＆More: Get a free Leap Year 2020 T-shirt at any of the retailers participating locations on Feb. 29—no purchase required.
●Foot Locker: Save 15 percent on purchases of $70 or more through Feb. 29.
●Expedia: Save up to 29 percent off select hotels worldwide with reservations made on the Expedia mobile app on or before Feb. 29. Some restrictions apply.
●Avis: Take $25 off the cost of a weekly car rental with code MUWA169 through March 30.
●Marriott: Enjoy up to 20 percent in savings when you use code ADP to book a room in advance through March 19.
1.Why is there an extra day in February 2020?
A.To remain in line with the true astronomical year.
B.To officially celebrate a special occasion.
C.To pass down a time-honored tradition.
D.To offer a business promotional opportunity.
2.How much will you pay for a pair of shoes priced at $100 on Feb. 29?
A.$15. B.$85.
C.$75. D.$70.
3.Which of the following offers discounts beyond Feb. 29?
A.Dog Hans. B.Legal Sea Foods.
C.Expedia. D.Marriott.
很定你是李华，你正在为高考紧张复习，但最近你遇到了-些问题以至学习低效。于是你给你校的外籍心理老师Charlie写一封求助信寻求帮助。要点如下：
1.写信意图；
2.存在问题；
3.希望得到帮助。
注意：1.词数100左右；
2.可以适当增加细节，以使行文流畅。
Dear Charlie,
_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
假定英语课上老师要求同学们交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。错误仅涉及一个单词的增加、删除或修改。
增加：在缺词处加一个漏字符号（^），并在其下面写出该加的词。
删除：把多余的词用斜线（\）划掉。
修改：在错的词下划一横线，并在该词下面写出修改后的词。
注意：1.每处错误及其修改均仅限一词；
2.只允许修改10处，多者（从第11处起）不计分。
Basketball fans around the world are mourning the dead of American superstar Kobe Bryant. Bryant killed in a helicopter crash last Sunday in California, along with her l3-year-old daughter Gianna and seven other people, Bryant was an 18-time All-Star player. He won five NBA championship and two Olympic gold medals. He was wide considered one of the great basketball players of his generation during his 20-year career with the Los Angeles Lakers. The helicopter carry Bryant and the others crash into a hilly area in foggy conditions outside Los Angeles. The cause for the crash is under an investigation.
阅读下而材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。
Dressed in n flowing long robe 1.（decorate）with floral embroidery（花卉刺绣）from a past era, stylist Xiao Hang looks like she surfaced from a time machine. She walks across the noisy Beijing subway, 2.（attract）curious glances and questions.
China 3.（welcome）western fashion and futuristic technology during the last decades, 4. a growing number of young people like Xiao are looking to the past for their dressing choices. 5.（obvious）, they prefer to put on traditional “hanfu”, or “Han clothing”.
These historic 6.（costume）of the Han ethnic majority are enjoying a renaissance because the government is promoting traditional culture. Period dramas have also contributed to a 7.（great）interest in traditional Chinese clothing and a higher demand for it.
Xiao, who used to work at a state-owned machine manufacturing company，now runs her own hanfu business,8. she dresses customers for photo shoots and even plans hanfu-style weddings. However, there is some way before the style reaches wide 9.（accept）in China. Many people say their hesitation is due to the odd looks they get when wearing hanfu 10. public.
