Human beings are the greatest threat to the survival of endangered species through hunting, habitat destruction and the effects of climate change.
Read on to learn which beautiful creatures are most in need of our help, protection and conservation.
Amur Leopard
Since 1996, the amur leopard has been classified by the IUCN as Critically Endangered with less than 70 individuals thought to exist today. It is hunted and killed for its beautiful fur. Its habitat is being destroyed for human settlement and agricultural practices.
Gorillas
Cross River Gorillas and Mountain Gorillas are both classified as Critically Endangered and Endangered by the TUCN since 1996—that is two out of five gorilla subspecies. There are currently only 200—300 Cross River Gorillas left in the wild, and 900 Mountain Gorillas.
Sea turtles
Two types of sea turtles are amongst the most endangered species in the world: the Hawksbill Turtle and the Leatherback Turtle. In the past 100 years, the Hawksbill Turtle has lost 90 percent of its population, 80 percent of which has been lost in the past 10 years. As of 1996, the IUCN classified it as a Critically Endangered species. The Leatherback turtle is listed by the IUCN as Vulnerable, yet many subpopulations are facing extinction.
Orangutan
Since the millennium, the Sumatran Orangutan has been classified by the IUCN as Critically Endangered with approximately 80% of the population lost in the past 75 years mainly as a result of mass deforestation. This awful trend continues to put pressure on the remaining population of 6,600 Sumatran Orangutans that are estimated to remain on this Earth.
It's common for some high school students to need the help of a math teacher. For others, numbers come naturally. And then there's Tamar Barabi. The Israeli teenager just invented a new geometric theorem(几何定理).
Like most discoveries, the moment happened by accident. Tamar handed in her math homework and the teacher said the theory she used to solve the problem didn't actually exist. "She said if I could prove it, it could be my theory. So that's what happened,"Barabi said. With help from her dad, who is also a math teacher, they sent the theorem to experts around the world.
Known as the Three Radii Theorem, or" Tamar's Theory" for short, it goes as follows:" If three or more equal lines leave a single point and reach the boundary(边界)of a circle, the point is the center of the circle and the lines are its radii(半径). "To create the actual theorem, Barabi had to write up three proofs, a series of conclusions and some sample exercises.
"Tamar deserves praise for finding a new twist of stating that a circle has only one center and only one radius," Professor Ron Livne said. "It's cool to see how Tamar's theorem can give elegant proofs for other important theorems."
When she's not coming up with new math theorems, Barabi spends most of her time after school taking ballet lessons. She also plays the guitar and the piano. When asked if she liked Justin Bieber, Barabi, who comes from the same town as supermodel Bar Refaeli, she just laughed. "I want to be an actor and a dancer," she said. For now, the teenager is enjoying the fame this new theory has afforded her.
So did her math teacher give her an A+ for her discovery?" No,"Barabi explained, "learn in a school where we don't get grades."
Researchers from China and the United States have found what makes ginkgo (银杏) trees live for more than 1, 000 years, according to a newspaper report. Researchers from Beijing Forestry University, the University of North Texas and some other Chinese research institutions reported in the U. S. magazine Proceedings of National Academy of Sciences that they analyzed 34 ginkgo trees and divided them into three groups according to their ages. Compared with adult trees, the ancient trees, aging from 193 to 667 years, have thinner cambium (形成层) cell layers(细胞层). Cambium cells are layers of stem cells between the inside wood and outside bark changing into other tissue.
The old trees have a higher level of IAA, a plant growth regulator and growth-stimulating hormone, and a lower level of ABA, a growth-resisting hormone. However, the average cross-sectional area of trees at breast height in the ancient trees group has been increasing with aging, which shows the continuous cambial cells division.
Little difference was found when it comes to their ability to photosynthesize(光合作用), grow leaves, grow seeds or resist disease compared to younger trees, showing that the ancient trees group are actually in a healthy and mature state.
Lin Jinxing of Beijing Forestry University and an author of the study said that trees usually die from outside stress like pests. They found disease resistance-associated genes kept high expression in old trees, along with genes associated with the synthesis(合成) of protective compounds, showing that the old trees do not lose their ability to defend against outside stressors. The researchers concluded that the longevity(寿命)of ginkgo trees is a balance between the growing and aging processes, rather than being regulated by a single gene.
Tapping into the water cycle and producing electricity from rainy days could be one way to grow our renewable(可再生的）energy use.
Until now, scientists have been unable to get water droplets(雨滴) to produce a large amount of power—but we may finally have a breakthrough. While we're still a long way from umbrellas, the latest approach shows there might be a way to get power from rain showers at a level of efficiency(效率)that makes these systems practical.
New research has found a method that could produce enough power from a single droplet of rain to light up 100 LED bulbs. That's a big jump forward in efficiency in the field.
Scientists have been looking into this type of power production for years, but the physics of converting the energy of raindrops into electricity are much harder to do than getting the energy from a rising tide or a flowing stream.
One of the improvements the team built into their droplet-based electricity generator(发动机)(DEG) was the use of a polytetrafluoroethylene or PTFE film, which is able to accumulate a surface charge as it's continuously hit by water droplets, until it gradually reaches saturation(饱和). The team found that as water droplets hit the surface and spread out, the drops act as a "bridge" that connects two electrodes(电极). The droplet bridge in turn creates a closed-loop surface so that all of the collected energy can be released(释放). This approach could eventually be applied anywhere that water hits a solid surface, the researchers say—the hull of a boat, the inside of a water bottle, or the top of an umbrella. However, there's still plenty of work to do to get this ready for practical use, with the researchers hoping to have a prototype ready in the next five years.
An ice boat, or iceboat, is a boat fitted with skis or runners and built to travel over ice in much the same way that sailboats do on the water. Today, used mainly as racing vehicles, modern iceboats are supported by skate-like steel runners which enable them to hold the ice at high speed.
Traveling over ice by boat was firstly undertaken for the purpose of transporting goods and equipment. The first recorded ice sailing for pleasure or sport took place in Europe, and the use of iceboats for commercial purposes soon died altogether.
Most iceboats are built for one person only. There are different classes of the iceboat, the most well-known being the International DN class and the Skeeter class. Distinctions between classes are determined primarily by size and mast height.
People have done a lot to significantly reduce friction(摩擦) aerodynamically(空气动力学地). The runners are angled in such a way as to counter the lateral force of the wind on the sails. Once a certain level of force has been reached, the iceboat is pushed forward with such force that it actually goes faster than the wind.
High speed and cruel weather can combine to create a dangerous environment. This has led to the adoption of a set of strict rules and guidelines that all who engage in ice yachting, sailing, or racing are expected to be familiar with and follow at all times.
A. Safety is a very high priority.
B. They are of great use in colder places.
C. However, there are larger boats designed for two or more.
D. The newly designed iceboat can reach extremely high speeds.
E. Therefore, people are very cautious when using an ice boat.
F. The earliest iceboats were patterned after traditional sailboats.
G. The only exception to this was their use in transporting lighthouse workers during the winter.
It is closing in on my 54th birthday as I write this and I am reminded of a wonderful quote(语录), "What a wonderful life I've had. I only wish I'd realized it sooner." l was so blessed to grow up the way l did. I was1by a loving family. I seemed to have all of2as my playground: I took walks in the woods and went swimming in the lake every day during the summer. I did well in school and 3friendships that I still have to this day. I was4enough to go to college and learned so much there.
My life had its share of5too. I married young and6financially for years to support my family. Two of my three children were severely sick. And I realized that they would need to be 7for the rest of their lives here.8, raising them brought so much learning, laughter and9into my soul. In the end they became the greatest10in my life.
Still, it took me a long time to11this. I spent years making the12so many of us here make. I constantly13what my life would be like if only my life's circumstances were14. In the end I wasted so many days looking for a15that never came and not enjoying the "present" I had 16_me. It took me years to see that where you are is not as important as who you are and that17living with love can bring you more 18 than anything else in this life.
It is never too 19to realize how wonderful your life is. Always remember this20is God's gift to you. And how you live it is your gift to God.
Mardi Gras in New Orleans, also known as Fat Tuesday, is cultural scene like the US version of carnival(狂欢节). But there is some debate over it was NOLA or Mobile, Alabama that had the first Mardi Gras back in the 1700s.
Regardless of who did it first, few would argue that the New Orleans festival is the best. Though the celebration (hold) every year on the day before Ash Wednesday, the festivities last for months. It (begin)with social events in November, private balls on Thanksgiving Day and New Year's Eve, with parades(游行) and more private balls throughout January and early February.
Getting invites to some (organize) events isn't easy. But if you know someone or have much money, MOM's Ball and Orpheuscapade Ball are (frequent) ranked among the best. If you are enthusiastic music, check out the annual Galactic concert at the world-famous Tipitina's on Lundi Gras (the day before Mardi Gras).
When the big day arrives, it's best (plan) what you want to see. Longtime locals have a (prefer) for the Krewe of Muses Parade, the Rex &. Zulu Parade, and the Krewe of St. Anne and Krewe of Julu Parades. But, for our money, it doesn't get any (great) than watching the Mardi Gras Indians Parade.
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。
Some Senior 3 students can't study efficiently because of staying up late. What's more, many have anxiety, which also lead to the inefficiency of studying.
In the respect of the problem, l have some suggestion for them. First, they should have enough sleep, that is of great importance. Beside, striking a balance between study and relaxation is necessarily. Finally, it's a great idea to them to spend more time doing sports.
In my opinion, more attention should paid to Senior 3 students' health. I suggest they take care of them so that they can stay healthy and study good.
1）自我介绍﹔
2）你的优势
3）期待回复。
注意：1）词数100左右;
2）可以适当增加细节，以使行文连贯。
