1 . Blind people have long desired for brightness, but scientists don’t have the technology. To bring that one step closer to reality, Zhiyong Fan, a materials scientist of the Hong Kong University of Science and Technology, developed a new artificial eye recently. The device, which is about as sensitive to light and has sharper vision and a faster reaction time than a real eyeball, may outperform human eyes.

The human eye owes its wide field of view and clear eyesight to the retina (视网膜) — an area at the back of the eyeball covered in light-detecting cells. The design for a new artificial eye is based on the structure of the human eye and uses a friendly light-sensitive material. At the back of the eyeball, an artificial retina is lined with Nan scale light sensors (纳米级光感器). Those sensors measure light that passes through the lens (晶状体) at the front of the eye. Wires attached to the back of the retina send signals from those sensors to the processor, similar to the way nerve networks connect the eyeball to the brain.

“In the future, we can use this to replace damaged human eyes,” says the lead designer. In theory, this artificial eye could see more clearly than the human eye, because the artificial retina contains about 460 million light sensors per square centimeter while a real retina has about 10 million light-detecting cells per square centimeter. Besides, the artificial eyeball records changes in lighting faster than human eyes can — within about 30 to 40 milliseconds, rather than 40 to 150 milliseconds. Although its 100-degree field of view isn’t as broad as the150 degrees a human eye can take in, the device can see as well as the human eye in poor light.

Hongrui Jiang, an electrical engineer at the University of Wisconsin, though, thinks engineers need a much more practical and efficient way to produce vast series of tiny wires on the back of the artificial eyeball to give it superhuman sight, which is super hard to achieve.

I am Li Hua from Class One, Senior Two.

Yours Sincerely,

Li Hua

As the saying goes, chances preferred the prepared mind. I learned this from one of my experience.

I was not chosen as member of the volleyball team of our school. Because of this, I decided to give up play volleyball. Lucky, my best friend stopped me but pointed out that it was my laziness and poor preparation which led to my failure. After that, I practiced playing the volleyball every day. When another tryout arrived, I was fully prepared and tried my best. As a result, I was selected and became an important player on our school team.

From this, I am firmly convincing that, no matter when chances arrive, we were able to seize them as long as we get well prepared.

In our daily life, we often meet with difficulties. Some people do nothing but wait, while     1     try hard to overcome. Personally, we should face with difficulties positively and make every effort to overcome them.

My memory drew me back to five years ago when I was a middle school student. At that time, I had great trouble    2     (study) English. First of all, I felt it hard to memorize English     3     (word). Besides I didn’t dare to say anything in class when     4     (ask) questions. What annoyed me most was that I failed exams     5     (constant). I was about to give up     6     my English teacher found my problems. He encouraged me and gave me some good advice. So     7     (inspire) by him, I decided to settle my problems.     8     (follow) his advice, I made progress gradually. I owe my achievement     9    the teacher whose encouragement was of great     10     (important).

I have a younger sister and his name is Xiaomei. She is a youngest member of my family. She was small, but she is the most important member of my family. Everyone love her a lot. Xiaomei is a very much good student. She is in the second grade, but she is so smart. She can learning anything very quickly. She often likes to go the kitchen to help Mom with the cooking. She loves dancing and singing song. She always fills the entirely house with laughter. She is the treasure of my family.

8 . Are you too old for fairy tales? If you think so, Copenhagen is sure to change your mind.

See the city first from the water. In the harbor sits Denmark’s best-known landmark: the Little Mermaid. Remember her? In one of Andersen’s fairy tales, she left the world of the Sea People in search of a human soul. From the harbor you can get a feel for “the city of green spires”. In cloudy weather, the copper-covered spires of old castles and churches give the city a dream-like atmosphere; you’ll think you’ve stepped into a watercolor painting.

Copenhagen is a city on a human scale (人性化的). You don’t have to hurry to walk in the city’s centre in less than an hour. Exploring it will take much longer. Copenhagen was the first city to declare a street for pedestrians (行人) only. The city has less traffic noise and pollution than any other European capital.

Churches and castles are almost all that remain of the original city. Copenhagen became the capital city in 1445. During the late 16^th century , trade grew, and so did the city. But fires in 1728and 1795 destroyed the old wooden structures. Much of what we see today dates from the 19^th century.