Birds in cities are damaging their health by trying to sing above the noise of urban life.     New research shows that male birds are trying to compete against traffic and city sounds.They are now singing louder and at higher frequencies,which could harm their vocal cords .Some birds are choosing to sing at night instead of during the day.This makes them more open to attack and also creates stress and exhaustion.    "The difference between urban and rural birdsong is becoming so big that the two groups could now be unable to communicate.This could lead to inbreeding and a weak gene poo1."said Dr Sue Anne Zollinger of the.University of St Andrews.     According to Zollingar,a bird group with a small gene pool might adapt less quickly to new diseases and could be wiped out.     A study of the dawn chorus found that birds in Berlin sang up to 14 decibels louder than those in the forest.The birds sang loudest on weekday mornings. "By trying to sing over the sound of the city,birds ale rising vocal injury,"said Zollinger."All this puts the same strain on a bird's vocal cords as when a human need to shout to be heard--except that the birds are doing it all day,every day,"she said.    "Singing under such pressure means birds have less control over the sound they produce.Their songs may lose quality and become more rough--sounding."said Zollinger.This could make them appear less attractive to female birds.     Mark Constantine,author of The Sound Approach to Birding,said:"Birdsong is important for our quality of life and has been proved to reduce our blood pressure.When we live in the centre of large,urban areas,we get stressed and it's extremely good to have birdsong around us.The impact on humans of birdsong is massive.It harms us,as well as the birds,if their songs become louder and simpler. According to Dr Sue Anne Zollinger,birds singing louder might eventually lead to   _  . A) the harm done to man's health B) the dying out of a species C) the serious damage to the bird's vocal cords D) the decrease of the birth rate of a bird group
B


American Girl It's packed with the things that matter most to girls: party plans, games, crafts and girl-to-girl advice. American Girlis an appealing, age-appropriate teen magazine that allows young girls to be themselves. The magazine features fun contests, puzzles, giggles, and more! Stories, creative games, cool contests and great sports tips for girls aged 7-11 are available in each issue ofAmerican Girl magazine. Issues per year: 6     Cover price: $ 27.95     Sale price: $22.95 Ladybug Beautiful, colorful, and delightful to read, each issue is filled with charming read-aloud stories, games for memory and skill building, songs, poems, and activities for beginning readers. Parents can visit our online Parents Companion that recommends additional activities, crafts, and books. Issues per year: 9     Cover price: $44.50      Sale price: $33.95 Cicada A monthly magazine for teenagers and young adults aged 14 and up. It offers high-quality fiction and poetry dealing with the issue of growing up, leaving the joys and pains of childhood behind, and becoming an adult. Cicadamagazine also encourages its teen readers to submit their own writing for publication. It's so inspiring and humorous that you will not be able to put it down. Issues per year: 6   Cover price: $51.00   Sale price: $33.95 Sorts Illustrated for Kids It covers sports kids like. Featuring interviews with sports heroes, entertaining comics, breathtaking action photos, tips from the pros  , news items of recent notes, games, puzzles, cartoons, fiction, advice from athletes, etc.Sports Illustrated for Kidsis a magazine for children aged 8 and up. Issues per year: 12      Cover price: $47.88      Sale price: $ 24.95 If you order a magazine with interviews with sports heroes for one year, how much can you save? A) $5.00 B) $10.55 C) $17.05 D) $22.93
D


Q: There are no exact differences between physics and other natural sciences because all sciences overlap .In general,however,physics is the scientific study of forces and qualities such as heat,light,sound,pressure,gravity and electricity,and the ways they affect other objects. One major branch of physics deals with the states of matter--solids,liquids and gases and with their motions.The pioneer achievements of Galileo,Kepler and Newton dealt with solid masses of matter in motion.Such studies deal with forces acting on moving objects.It is the subject of mechanics and belongs to the branch of mechanics called dynamics,the study of matter in motion.This large topic includes not only the motions of stars and ping-pong balls but also the motions of the water pumped by a fire engine and those of the air passing through the jet engine of an airplane. A branch of mechanics is statics ,the study of matter at rest.The designs of buildings and bridges are examples of problems in statics.Other branches of physics are based on the different kinds of energy,which interact with matter.They deal with electricity and magnetism ,heat,light,and sound.From these branches of physics scientists find clues  which have revealed  the constructions of atoms and how the atoms react to various kinds of energy. _ is often called the basis of modern physics.Among the many subdivisions of modern physics are electronics and nuclear physics.Physics is closely related to engineering.A person who uses knowledge of physics in solving everyday problems is often called an engineer.For example,electricity is one of the branches of physics;and an electrical engineer is a man who uses the "natural laws" of electricity to help in designing and electric generator . Among many branches of modern physics is   _  . A) states B) electricity C) electronics D) mechanics
A: C


(Question)
Over a hundred years ago people in London were surprised to see a very unusual boat come sailing up the Thames River.The boat was eighty feet long flat-bottomed,with big wooden eyes on both sides in the front and was colorfully painted at the back. People came to know that it was a sailing boat from Fuzhou in distant China.The boat had sailed round the Cape of Good Hope  up the western coast of Africa,and finally to England.It had covered fifteen thousand miles--more than half of the distance round the world. Although it was unexpected,the Chinese were warmly welcomed.The boat carried goods such as silk and tea as well as a number of gifts from the Emperor of China for the Queen of England. People had always mistakenly thought of the Chinese as a people not used to sea.However,from centuries of trading and sailing in dangerous seas,the Chinese had learned how to build good boats and sailed them well.The coming of this sailing boat to London proved once again that the Chinese could sail to distant countries in the world. .The writer wants to prove that a long time ago the Chinese   _  . A) carried silk,tea and other goods to England B) could reach many parts of the world by sea C) could sail along the Thames River D) surprised Londoners with an unusual boat
(Answer)

B