问题 选择题

下列实例中,属于减少惯性的不利影响的是(  )

A.跳远运动员跳远时助跑

B.劳动时,斧头松了,把手柄的下端撞击树墩,使斧头被套牢

C.小型汽车驾驶员驾车时必须系好安全带

D.用力拍打刚晒过的被子使灰尘落下

答案

答案:C

题目分析:

A、跳远运动员跳远时助跑,即原来运动员是运动的,当其起跳后,由于惯性,会仍然保持运动状态,所以可以取得更好的成绩,是惯性的有利影响,不符合题意;

B、锤头松动时,把锤柄的一端在水泥地上撞几下,即该过程中,锤头和锤柄都处于运动状态,当锤柄撞击到地面时运动停止,而锤头由于惯性仍保持运动状态,从而使锤头套紧,是利用惯性的有利影响,不符合题意;

C、驾驶员和前排乘客系安全带是为了防止由于惯性而被撞伤,属于防止惯性的不利影响,符合题意;

D、拍打被子时,被子运动,而灰尘由于惯性仍保持原来的静止状态,再由于重力的作用而脱离衣服,是利用惯性的有利影响,不符合题意;

故选C.

阅读理解

Every year thousands of tourists visit Pompeii, Italy. They see the sight that Pompeii is famous for—its stadium and theaters, its shops and restaurants. The tourists do not, however, see Pompeii’s people. No one has lived in Pompeii for almost 2,ooo years.

Once Pompeii was a busy city of 22,000 people. It lay at the foot of Mt Vesuvius, a grass-covered volcano. Mt Vesuvius had not erupted for centuries, so the people of Pompeii felt safe. But they were not. In August of the year 79 AD, Mt Vesuvius erupted. The entire top of the mountain exploded, and a huge black cloud rose into the air. Soon stones and hot ashes began to fall on Pompeii. When the eruption ended two days later, Pompeii was buried under 20 feet of stones and ashes. Almost all of its people were dead.

For centuries, Pompeii lay buried under stones and ashes. Then in the year 1861, an Italian scientist named Ginseppe began to uncover Pompeii. Slowly, carefully, Ginseppe and his men dug. The city almost looked the same as it had looked in 79 AD. There were streets and fountains, houses and shops. There was a stadium with 20,000 seats. Perhaps the most important of all, there were everyday objects, which tell us a great deal about the people who lived in Pompeii. Many glasses and jars had some dark blue color in the bottom, so we know that the people of Pompeii liked wine. They liked bread too; metal bread pans were in every bakery. In one bakery there were 81 round, flat loaves of bread—a type of bread that is still sold in Italy today. Tiny boxes filled with a dark, shiny powder tell us that women liked to wear eye-makeup.

Ginseppe has died, but his work continues. One-fourth has not been uncovered yet. Scientists are still digging, still making discoveries that draw the tourists to Pompeii.

小题1:Why do large number of people come to Pompeii each year?

A.To visit the volcano.

B.To shop and eat there.

C.To watch sports and plays.

D.To see how Pompeiians lived.小题2:Why did the city uncovered look almost the same as it had looked in 79 AD ?

A.Because Ginseppe and his men dug it slowly and carefully.

B.Because the city was buried alive and remained untouched.

C.Because scientists successfully rebuilt the city with everyday objects.

D.Because nobody had lived in the city ever since the volcano erupted.小题3:What do we know about the Pompeiians who lived 2,000 years ago?

A. They lived more or less the same as Italians now do.

B. They liked women wearing all kinds of makeup.

C. They enjoyed a lazy life with drinking and eating.

D. They went back to Pompeii after the eruption in 79 AD.

单项选择题