Exposing living tissue to subfreezing temperatures for long can cause permanent damage. Microscopic ice crystals (结晶体) cut cells and seize moisture (潮气), making donor organs unsuitable for transplantation. Thus, organs can be made cold for only a few hours ahead of a procedure. But a set of lasting new antifreeze compounds (化合物)—similar to those found in particularly hardy (耐寒的) animals—could lengthen organs’ shelf life.
Scientists at the University of Warwick in England were inspired by proteins in some species of Arctic fish, wood frogs and other organisms that prevent blood from freezing, allowing them to flourish in extreme cold. Previous research had shown these natural antifreeze molecules (分子) could preserve rat hearts at -1.3 degrees Celsius for up to 24 hours. But these proteins are expensive to extract (提取) and highly poisonous to some species. “For a long time everyone assumed you had to make synthetic (人造的) alternatives that looked exactly like antifreeze proteins to solve this problem, ”says Matthew Gibson, a chemist at Warwick who co-authored the new research. “But we found that you can design new molecules that function like antifreeze proteins but do not necessarily look like them. ”
Most natural antifreeze molecules have a mixture of regions that either attract or repel water. Scientists do not know exactly how this process prevents ice crystal formation, but Gibson thinks it might throw water molecules into push-pull chaos that prevents them from tuning into ice. To copy this mechanism, he and his colleagues synthesized spiral-shaped molecules that were mostly water-repellent—but had iron atoms at their centers that made them hydrophilic, or water-loving. The resulting compounds were surprisingly effective at stopping ice crystals from forming. Some were also harmless to the roundworm Caenorhabditis elegans, indicating they might be safe for other animals.
“These compounds are really cool because they are not proteins—they are other types of molecules that nonetheless can do at least part of what natural antifreeze proteins do, ”says Clara do Amaral, a biologist at Mount St. Joseph University, who was not involved in the research. Gibson’s antifreeze compounds will still need to be tested in humans, however, and may be only part of a solution. “We don’t have the whole picture yet, ”do Amaral adds. “It’s not just one magical compound that helps freeze-tolerant organisms survive. It’s a whole suite of adaptations.
1.What will happen if organs are kept for a long time in temperatures below zero?
A.They will have ice crystal formation inside.
B.They will not suffer permanent damage.
C.They will have longer shelf life.
D.They will be fit for transplantation.
2.What can we learn about natural antifreeze proteins?
A.They look like Gibson’s antifreeze compounds.
B.They are composed of antifreeze molecules harmless to other species.
C.They are spiral-shaped and have iron atoms at their centers.
D.They can be found in organisms living in freezing cold weather.
3.How are antifreeze molecules prevented from ice crystals?
A.By creating compounds both water-repellent and water-loving.
B.By extracting the proteins from some hardy animals.
C.By making synthetic alternatives like antifreeze proteins.
D.By copying spiral-shaped molecules mostly water-resistant.
4.What’s the main idea of the passage?
A.Push-pull chaos might prevent water molecules from turning into ice.
B.The final solution to preserving donor organs has been found recently.
C.Chemicals inspired by Arctic animals could lengthen organs’ shelf life.
D.Gibson’s antifreeze compounds can do what natural antifreeze proteins do.
Having an older brother comes with plenty of benefits. Big brothers tend to look out for their younger siblings(兄弟姐妹）,and despite the occasional rocky moment here and there, many siblings enjoy life-long close relationships. However, a new study finds an interesting downside: children with older brothers take longer when it comes to developing language skills.
The study, conducted by a group of researchers in Paris, France, builds upon earlier research that had already established that having older siblings is associated with poor linguistic(语言的）development. Now, researchers say they have come to a more specific conclusion: only children with an older brother exhibit these linguistic difficulties.
One would assume that children with older brothers would grow up around more conversation on a daily basis, thus speeding up their language development. Yet researchers say such children actually take longer than their older brothers to begin developing these skills.
Researchers studied more than 1,000 children from birth to the age of five-and-a-half years old. Each child’s language skills were tested at ages 2,3,and 5.5,using tests specially designed to measure numerous aspects of language development such as vocabulary, syntax, and verbal reasoning.
What the research team discovered was significant: children with an older brother had, on average, a two-month delay in their language development compared to those with an older sister.
As far as explaining this phenomenon, researchers have proposed two hypotheses(假设).The first is that older sisters tend to talk more often than older brothers, which would compensate for parents potentially being less present than they were for their first child. The second hypothesis is that older sisters usually compete with their siblings less than older brothers for their parents’ attention.
As of now, the study’s authors say they can’t say for certain why children with older brothers have a harder time developing language skills. In the future they would like to investigate if culture or location affects the results of these studies.
1.What does the underlined word“downside”in paragraph 1 mean?
A.difficulty B.drawback C.mistake D.burden
2.What does the previous research suggest about older siblings?
A.Having older siblings will affect the younger one’s language development.
B.Many children prefer having brothers and sisters.
C.Older brothers may have something to do with the linguistic difficulties.
D.Children with older siblings would grow up around more conversation.
3.Why do children with older brothers experience the delay in language development?
A.Parents tend to focus more on the first child.
B.Older sisters are more caring than older brothers.
C.Older brothers always seek to get more attention from their parents.
D.Younger children are always ignored by their older brothers.
4.What will further research of the study focus on?
A.The reasons for children’s delay in language development.
B.Other aspects that may influence the outcomes of the study.
C.More assumptions to explain the phenomenon.
D.The effect of culture on children’s language learning.
In one of my favorite photographs of my mother, she's about 18 and very tall, with long, blond hair. It's the 1970s and my dad is there, too, hugging her from behind．
I haven't seen this photo for years. I have no idea where it is now, but I still think of it and, specifically, my mom is in it. She looks so young and innocent. At that time she hasn't yet dropped out of college, or got married. The young woman in this photo has no idea that life will bring her five children and five grandchildren, one divorce, two marriages and a move across the country．
For me, as for many daughters, the time before my mother became a mother is a string of stories, told and retold: the time she sold her childhood Barbie doll to buy a ticket to Woodstock; the time she worked as a waitress at Howard Johnson's, struggling to pay her way through her first year at Rutgers. The old photos of her are even more appealing than the stories because they're a historical record, carrying the weight of fact．
It is always a comfort from those photos to know that time, aging and motherhood cannot take away a woman's essential identity. For daughters who closely resemble their moms, it must be an even bigger comfort: these mothers and daughters are twins, separated by a generation ,and an old photo serves as a kind of mirror．
For daughters, these old photos of our mothers feel like both a chasm(巨大差异)and a bridge. The woman in the picture is someone other than the woman we know. She is also exactly the person in the photo-still, right now. Finally, we see that the woman we've come to think of as Mom-whether she's nurturing(养育), or disapproving, or thoughtful, or supportive, or sentimental--is also a mysterious, fun, brave babe．
She's been here all this time.
1.What can we know about the author's mother from paragraphs 2&3?
A.She divorced twice all her life
B.Life was tough for her during her first year at college
C.She traveled across the country in her youth
D.She was good at storytelling
2.Why does the author find the photo of her mother appealing?
A.The photo reminds her of her mother
B.Her mother looks young and happy in the photo
C.She wonders why her mother dropped out of college
D.The photo tells a lot about her mother in her youth
3.Some photos of mothers bring comfort to their daughters because________.
A.the photos are kept well even after generations
B.the photos record the life of the mothers faithfully
C.the photos help daughters to learn more about their mothers
D.the photos show the essential part of the mothers remains unchanged
4.Which one could be the best title of the passage?
A.The Pictures of Our Mothers
B.Our Mothers as We Never Saw Them
C.My Favorite Picture of My Mother
D.The Way to Learn About Our Mothers
Enter the 17th Annual Kids’ Fish Art Contest
Each fall, Ontario students are invited to enter the Kids’ Fish Art Contest．This free annual contest lets you show off your artistic talents and learn about Ontario’s native fish and their habitats．
The contest is open to all students：
●who are residents of Ontario
●currently attending elementary or secondary school(or homeschooled)
●between the grades of 4-12
Children of Ministry of Natural Resources and Forestry’s Fish and Wildlife Services Branch employees are not permitted．
Prizes
There is 1 winner for each of the 3 categories：
●grades of 4-6 ●grades of 7-9 ●grades of 10-12
This year’s prizes include：
●a fishing trip at Brennan Harbour Resort
●a day of fishing with Canadian Sport fishing Television Show Host, Italo Labignan
●the winning designs advance to an international competition
Key dates
Opens: September 30,2019
Closes: December 6,2019
Announcement of winners: March 2020
How to enter
1.Prepare your entry：
●original artwork ●a short essay
2.Download and complete the entry form．
3.Mail your entry, postmarked no later than December 6,2019
To: Ontario Ministry of Natural Resources and Forestry
Kids’Fish Art Contest
Peter borough ON K9J 3C7
Do：
●provide your artistic interpretation of the fish in its habitat
●submit your original, hand-done creation
Do not：
●use photographs, tracings, computer-generated artwork
●submit freehand copies of other people’s work
●put any lettering, signatures or initials on the front of the design
Essay
Write a 1-page essay about：
●your fish ●its habitat ●how to protect it for future generations
Include your name and address on your essay．
1.Who can sigh up for the contest?
A.Julie, a 3 grader from Ontario B.Ian, whose father works with the contest
C.Brian, a 6-grade homeschooler D.Olivia, who lives outside of Ontario
2.When will the winning entries come out?
A.September 30,2019 B.December 6,2019．
C.March 2020 D.December 31,2019．
3.To enter the contest, participants must_______
A.mail the entry form to the contest holder
B.put their names on their artworks
C.ensure their entries are received by December 6,2019
D.create their artworks by hand
假如你是李华，五月份去美国参加“国际文化周”，你的美国笔友Tom来信询问你赴美相关事宜。请你写一封回信，内容包括：
1. 活动时间、地点；
2. 活动的、内容；
3. 其他个人安排。
注意：1. 词数100左右。
2. 可适当增加细节，以使行文连贯。
参考词汇：International Culture week国际文化周
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假定英语课上老师要求同桌之间互相修改作文，请你修改你同桌写的以下作文。文中共有十处语言错误，每句中最多有两处。错误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：在错的词下面画横线，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1词；
2.只允许修改10处，多者（从第11处起）不计分。
Dear Steven,
From your letter, I know it is hard for you to make friends. The following advice may be for some help to you.
To begin with, walking to your classmates and talk with them. After several talk you will happy find that they ate likely to consider you as a warm-heart person. Gradually, you will enjoy each other company. Besides, you’d better to give them a hand when they are in trouble. It is advisable to participate in different kind of activities, which you can communicate with different people.
All in al if you follow my advice above, you would find that it isn’t big deal to make some friends.
Yours,
Jack
