Merry Christmas

The winter holiday season is the most festive time of the year in the United States. Students from elementary school through college have about two weeks’ vacation, beginning shortly before Christmas and ending soon after New Year’s Day.   71  There are many parties to celebrate the birth of Christ and the arrival of the New Year.

72 Late in November, street lights and store windows are decorated with the traditional Christmas colors of red and green. Santa Claus, shepherd and angel scenes appear in shop windows. Winter scenes with snowmen, sleighs, skaters, and skiers decorate cards and windows.

The manufacture and sale of Christmas items is big business.   73  Smart shoppers buy their gifts far in advance, before the Christmas rush makes shopping a chore.

Although Americans enjoy the commercial friendliness of Christmas, the most beautiful and meaningful parts of the holiday occur at home.   74  Then they sit down to enjoy a traditional Christmas dinner—turkey or ham, sweet potatoes, vegetables, and cranberry sauce. Dessert is usually fruit cake, plum pudding, or apple pie. Most of the Christmas customs which Americans enjoy today are variations of traditions brought here by European immigrants, decorating the Home with evergreens for example.  75  Branches of evergreens were thought to bring good luck and guarantee the return of spring. Now, at Christmastime, decorated trees stand in about two-thirds of American homes. The modern American tree is usually covered with colored balls and strings of colored lights.

A.   Many families gather around the tree and open their gifts.

B.   In America, the spirit of Christmas arrives about a month before the holiday itself.

C.   Many families go away for the holidays, but those who stay home have fun, too.

D. In America, it’s customary to exchange gifts with family members and close friends.

E. Stores depend on Christmas shoppers for about one-fourth of their annual sales.

F. Today the custom continues, but now it is for fun.

G. This winter custom began in ancient times.

Urban grasshoppers change their tune for females

grasshopper

Grasshoppers that live in noisy urban environments are having to change their song, a study has found.

Researchers suggest that high levels of background noise may affect the grasshoppers’ mating process. They say the insects are forced to increase the volume of the low-frequency sections of their call. Results of the study, by scientists from the University of Bielefeld, Germany, are published in the journal Functional Ecology. The research, which shows traffic noise could upset bow-winged grasshoppers’ (Chorthippus biguttulus) mating system, is the first of its kind, according to lead researcher Ulrike Lampe.

"Effects of man-made noise on communication has only been studied with vertebrates(脊椎动物), so far," said Ms Lampe, a PhD student at the University of Bielefeld’s Department of Evolutionary Biology. The scientists caught 188 male bow-winged grasshoppers from noisy roadsides and quiet rural locations.

According to Ms Lampe: "Bow-winged grasshoppers are a good model organism to study sexual selection because females can respond to male loving songs with their own low-frequency signal, if they are attracted to a male song." The grasshoppers produce their mating call by rubbing a toothed file on their hind-legs against a vein that is located on their front wings. The male’s song consists of short phrases of two to three seconds. The first part of the call consists of slower ticking sounds that increase in speed, leading to a buzzing sound towards the end of the phrase.

In order to stimulate the males to begin mating calls, scientists exposed the males to a female and recorded the results in the laboratory. The team then analysed the differences between the results of each group of grasshoppers. “Results showed that compared to males from rural locations, urban grasshoppers shift the frequency peak of the lower part of their spectrum(频谱) upwards," Ms Lampe explained. This would make sense to avoid low-frequency noise, as traffic noise could mask signals in that part of the frequency spectrum. The team’s findings demonstrate that traffic noise could be upsetting the grasshopper’s mating system."Increased noise levels could affect grasshopper courtship in several ways," commented Ms Lampe. "It could prevent females from hearing male loving songs properly, prevent females from recognising males of their own species, or impair females’ ability to estimate how attractive a male is from his song."

67. What is the usage of the grasshoppers’ songs?

A. To make our urban hear better.

B. To attract the mate grasshoppers.

C. To fight against the urban noise.

D. To attract the female grasshoppers.

68. How did scientist prove their conclusion?

A. By using statistics.

B. By arguing a topic.

C. By quoting person’s theory.

D. By comparing the results.

69. What does the underlined word “mask” mean?

A. Cover.    B. Affect.     C. Prevent.     D. Destroy.

70. What can be inferred from the passage?

A. Urban environment affects some animal lives.

B. Urban grasshoppers have to change their tune.

C. Grasshoppers shift the peak of spectrum.

D. Grasshoppers don’t like living in noisy urban areas.

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