The other day, I bought an expensive anti-aging cream that promised to make my face look several years younger that other women by fighting free radicals. It made me curious about what free radicals ares.Is the anti-aging cream the only way I need to protect myself?
“As a scientific term, free radicals are essentially unstable atoms, “says Arizona-based doctor, Natasha Bhuyan, M. D. “In medicine, they cause cells to break down over time and are linked to aging.”
A super simple chemistry review for you: Atoms from different elements are the building blocks that make up water, nitrogen and more. Electrons (电子) are the negatively charged atoms, and they like to be in pairs. When an electron loses its partner, it creates a free radical, which is usually unstable and highly reactive. Free radicals typically go through the body to seek out a replacement for their missing electron, and that can result in damage to cells,proteins and DNA.
So how do free radicals form and why do they happen? Bhuyan says, “Scientifically, free radicals are unpaired electrons that are seeking a mate to bond with. The theory behind free radicals is that they can lead to the imbalance between free radicals and antioxidants (抗氧化剂).” Another mini-science lesson for you: Antioxidants are natural or man made matters that can help delay or prevent some types of cell damage. They’re often found in fruits and vegetables.
A lot of the aspects of modern life — our diet, lifestyle and environmental factors like pollution, can cause oxidative stress. Over time, oxidative stress weakens cell and tissues and can leave you more easily to certain health issues including cancer. And, as beauty marketers are keenly aware,oxidative stress can also speed up the aging process. Now that your know free radicals can weak on your health, you’re probably wondering if there are any ways to prevent them from forming or at least to minimize their negative effects.
1.What does the author intend to do in paragraph 1?
A.Explain the process of aging. B.State the formation of free radicals.
C.Introduce the topic of free radicals. D.Describe the harm of anti aging cream.
2.Which of the following do free radicals refer to?
A.Unpaired electrons. B.Steady atoms.
C.Replacements of atoms. D.Functions of electrons.
3.What can we learn about antioxidants from the text?
A.They have never been found in nature.
B.They do harm to cells, proteins and DNA.
C.They can slow down the damage of some cells.
D.They always keep balance with free radical.
4.What will the author probably tell us next?
A.What exactly oxidative stress is. B.How beauty marketers promote sales.
C.Where a variety of diseases come from. D.Whether free radicals can be prevented.
On the last Monday in May, people in the United States celebrate Memorial Day. This federal holiday honors members of the American military who died at war. Schools and government offices close. Most people in the US have this day off from work. People celebrate Memorial Day with outdoor parades.
Most Americans consider it the start of summer though the season really begins in June. With so many people off work, Memorial Day has also become a popular shopping day. However, on most occasions Memorial Day is a serious and even sorrowful holiday. Those who have lost family members at war visit burial sites to decorate the graves. They place flowers, wreaths and US flags on the graves.
Memorial Day comes from a tradition that began after the US Civil War called Decoration Day. The Civil War was a very dark time in the US history. Historians have long thought that about 620,000 soldiers died in the fighting. However, new research suggests that the dead numbered about 750,000.
In 1868, about 5,000 people gathered at Arlington National Cemetery on the edge of Washington, D. C. They decorated more than 10,000 graves of Union and Confederate soldiers. They called it Decoration Day. bone
The tradition spread to other areas of the country. In 1873, New York State called it Memorial Day and was the first to make it a legal-holiday. Other States allowed, but not all. Some southern states had (and-still have) separate celebrations that honor only dead Confederate soldiers.
After World War I ended in 1918, Memorial Day became a day to honor all American soldiers killed at war. In 1971, Congress passed a law making it an official federal holiday all over America.
1.What's the purpose of Memorial Day in America?
A.To mark the start of summer. B.To let people enjoy themselves.
C.To show respect to dead soldiers. D.To set a holiday to encourage soldiers.
2.What's the atmosphere of American Memorial Day like on most occasions?
A.Sad. B.Casual.
C.Pleasant. D.Relaxing.
3.When did Memorial Casual, become a legal holiday throughout the US?
A.In 1971. B.In 1873.
C.In 1918. D.In 1868.
4.What is the best title for the text?
A.Celebration Activities of Memorial Day in the US
B.The Prospect of American Memorial Day
C.Members Honored on American Memorial Day
D.The Evolution on Memorial Day in the US
Alice is a senior at Sunset High School (SHS) in America.The kids in her school are looking forward to senior graduation and summer vacation.And they still desire to live a significant life: doing something worthwhile and making a difference.
Alice, senior class president, decides to take action by organizing a food drive. She also decides to reach out to the community in the neighborhood for support.
She wrote,“Hi! My name is Alice and I'm a senior at Sunset! The SHS student government is hosting a drive and collecting the canned and boxed food for needy families. I know many students in the slum (贫民窟) are not able to access regular meals without school. One-hundred percent of everything donated will go to families in need. So it would be amazing if anybody could donate any extra food and lay it around the house. I would be so happy to come by and pick up any extra food that anyone has and just let me know!”
So far, the community has made some 400 donations, and Alice has picked up each one.They're left in brown paper bags around their houses, and she handles them with the latest gloves. It's all packaged food, and the packaging is cleaned with disinfected wipes. Along with the rest of the student union, which brainstormed the idea last week, Alice is setting up distribution centers to dispense the food in the city so families can get what they need.
“In the community, I've seen so many people offering their help ,and I've picked up so many donations from community residents,”Alice said. It's nice to see people supporting each other.I think it's really good hat we're belong more cautious, especially within the community,Alice says.Every individual is aware of how to take care of themselves, their family and others them.They join hands make a big difference indeed. With everyone's efforts,the donation work goes on easily and smoothly and many poor families has got help.
1.What do we know about the students at SHS in the text?
A.They're eager for a meaningful life. B.They've helped to build a community.
C.They've graduated from senior high school. D.They're forced to do something worthwhile.
2.Why did Alice organize the food drive?
A.To gain greater popularity. B.To get food for families in need.
C.To set up the SHS student union. D.To donate food to the students in her school.
3.What does the underlined word“dispense”in paragraph 4 probably mean?
A.Recycle. B.Hand out.
C.Gain. D.Chew up.
4.What can be concluded from the last paragraph?
A.East or west, home is best. B.it's good to learn此another man's cost.
C.Actions speak louder than words. D.Many hands make work light.
If you hear the word“Castle” or the word“palace”，you may picture the same kind of building for both：large，made of stones，probably with a tower. And，of course，you're not entirely wrong，as those are features of both palaces and castles.
So then hay bother to visit one royal building in the United Kingdom Buckingham Palace and another the same country Windsor Castle?It turns out there is a difference，and you
can find it pretty plainly in these two popular buildings.
The Case for Castles
Castles were residences for royalty.But they were also intend as defensive seats. Say you're a king who has taken a particular area over.Now you have to hold it. castle and staff it with soldiers to defend your conquered territory and ensure it remains part of your kingdom.
Castles were built throughout Europe and the Middle East primarily for protection of the king and his people.Some common features of castles include：
●thick walls and heavy gates to keep invaders out
●protective low walls for archers to shoot with cover
●high towers for keeping a lookout over the surrounding
●gate houses for admitting allies instead of allowing enemies into the castle
The Place for Palaces
Palaces， on the contrary， had no defensive purposes.They were first meant for showing off the great victory of the war.Palaces were where the spoils(战利品) of war might be displayed,along with grand architecture,massive banquet halls,golden table settings and maybe even hundreds of luxuriously decorated rooms.
While kings certainly took up residence in palaces as well as castles,nonmilitary royals might also have lived in (or still live in)palaces. Ministers could live in castles to show the power of their riches rather than their nonexistent military power. The term comes from Palatine Hill in Rome.
1.Which of the flowing is one feature of castles?
A.Low towers surrounding castles.
B.Defensive low walls for shooting.
C.Gatehouses allowing enemies into the castle.
D.Thick walls and heavy gates to lock invaders in.
2.Why were palaces first built?
A.To accommodate ordinary soldiers.
B.To defend the king's conquered territory.
C.To show off the art of royal painting,
D.To display huge success of the war.
3.What is the main purpose of the next?
A.To list the reasons for kings living in palaces.
B.To make a comparison between castles and palaces.
C.To talk about The value of castles in modern times.
D.To show palaces are more popular than castles.
语法填空
Mr Johnson lived in the woods with his wife and children He owned 1.farm, which looked almost abandoned.2.(lucky)，he also had a cow which produced milk every day. He sold or exchanged some of the milk in the towns nearby 3.other food and made cheese and butter for the family with what 4.(leave). The cow was their only means of support, in fact. One day, the cow was eating grass 5.it began to rain heavily. While making great efforts to run away, she 6.(fall) over the hill and died. Then the Johnsons had to make a living 7.the cow. In order to support his family, Mr. Johnson began to plant herbs and vegetables. Since the plants took a while to grow, he started cutting down trees 8.(sell) the wood. Thinking about his children s clothes, he started growing cotton too. When harvest came around, he was already selling herbs, vegetables and cotton in the market 9.people from the towns met regularly. Now it occurred to10.that his farm had much potential and that the death of the cow was a bit of luck.
When two ninth-grade students found smoke coming out of the back of their school bus early Tuesday morning，their bus driver knew just what to do. Thanks to her_______thinking，more than 50 students' lives were_______.
While_______a group of 56 students to their middle school in Duncan，South Carolina，on Tuesday， Teresa Stroble noticed the heavy_______ rising from the back of her bus. She_______pulled the bus over，evacuated (疏散)the student, and radioed the transportation office to ask_______to call 911. Firefighters arrived at the scene shortly after the fire began and quickly_______the fire, which CBS News reports was so_______that people driving by were able to feel its heat inside their cars.Parents of the children on the bus were_______the fire, but thanks to Stroble，the news they received was all________not a single child had been hurt.
Since then， Stroble， who has been a bus driver for seven years ________also works as a teacher's assistant(助教)，has been________for her brave actions. " We are so ________of our bus driver, "headmaster Scott Turner told local CBS News.“She was________.She also kept the students calm.She made sure they were safe.She didn't leave the bus ________they all left .She is our ________today.”
The local fire department is still unsure what________the fire，but some say that this 1995 ________has been known to have wiring and electrical problems. ________，we were so happy that Stroble was able to ________on her feet and keep everyone safe and sound.
1.A.careful B.deep C.kind D.quick
2.A.saved B.shown C.gotten D.checked
3.A.bringing B.driving C.inviting D.walking
4.A.gas B.water C.smoke D.heat
5.A.gradually B.suddenly C.finally D.immediately
6.A.anyone B.someone C.everyone D.another
7.A.found out B.turned down C.put out D.cut down
8.A.large B.wide C.fast D.bright
9.A.tired of B.angry about C.surprised at D.worried about
10.A.new B.simple C.good D.active
11.A.or B.and C.but D.so
12.A.praised B.encouraged C.helped D.supported
13.A.sure B.fond C.certain D.proud
14.A.serious B.mad C.calm D.positive
15.A.after B.until C.if D.because
16.A.hero B.friend C.teacher D.leader
17.A.controlled B.fixed C.ordered D.caused
18.A.base B.bus C.source D.detail
19.A.Also B.Besides C.However D.Later
20.A.think B.run C.stand D.look
