题干

2015年6月1日晚,“东方之星”客轮在长江水域监利段发生翻沉,客轮倒扣在江面上.为了尽快救出被困者,搜救队员用铁锤敲击露在水面的船体并将耳朵贴在船体上听.下列有关说法正确的是(  )

A:敲击船体是为了使铁锤振动发声

B:敲击船体是利用声向被困者传递能量

C:贴在船体上听是为了听到求救的超声波信号

D:贴在船体上听是利用固体传声效果比气体好

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答案(点此获取答案解析)

D

同类题5

   A ban on smoking in most public places goes into effect(效果) on Sunday in China - home to a third of the world's smokers. That means around 300 million smokers will no longer be allowed to light their cigarettes in the "enclosed public places." These include hotels, restaurants, theaters and public transport waiting rooms. The ban does not cover offices or factories.
   The campaign is aimed at controlling(控制) the number of deaths from smoking-related illnesses, running at a million a year. According to the World Health Organization, more than 3,000 people die every day in China because of smoking. Health experts also hope it will help Chinese to raise the knowledge of the dangers of smoking.
   But the new rules have been criticized because they do not include punishments(处罚) for those who choose not to obey them.Most people worry that Chinese smoking ban may have little effect.
   Business owners often hate rules that force(强迫) them to ban smoking on their restaurants, bar, cafe..., because many customers(顾客) do not like the rules and complain. Often you find people smoking at the next table while you are eating your meal or having a drink in a bar.
It appears that many Chinese people don't know the dangers of smoking. Research suggests only one in four knows the harm(害处) cigarettes or second-hand smoke can cause.
   At the same time the government makes a lot of money from the sales of cigarettes by the state-owned firms that make and sell all tobacco products throughout the country.