问题 问答题

阅读下列声速与气温有关的小短文:

气温影响空气的疏密程度,气温高,空气的疏密程度小,则声音传播时的速度就大,因而声速与气温有关,由此产生声音不一定由声源沿直线传播的情况.晴天的中午地表温度迅速升高,地表附近的气温较上层的气温高,声音在地表附近的传播较上层快,于是在地面上的声源发出的声音向四周传播时是向上拐弯的.

那么试探究下列两种情景下声音的传播情况:

(1)赤日炎炎,穿越新疆罗布泊的沙漠或戈壁滩时,即使相距不太远的人也很难听清楚对方的大声喊叫,其中一个主要原因是声音在传播时向______(选填“上”、“中”或“下”)拐弯.

(2)我国古代诗人张继在《枫桥夜泊》中写到:“姑苏城外寒山寺,夜半钟声到客船”,若枫桥到寒山寺的距离为680m,客船里的乘客听到钟声至少是______s前僧人撞击钟面而传来的(假如当时的气温是15℃).地表温度比夜空温度______(选填“高”或“低”),钟声向______(选填“上”、“中”或“下”)拐弯,传播的距离______(选填“较远”、“一样”或“较近”).

答案

(1)因为地表附近的气温较上层的气温高,声音在空气中传播时总爱拣温度低的路径,所以人的说话声会拐向高空,其结果就是相距不太远的人也听不清对方的喊叫声了.

(2)∵v=

s
t

∴客船里的乘客听到钟声需要的时间是t=

s
v
=
680m
340m/s
=2s,

深夜空气温度比地表温度高,即寺内温度高而枫桥河畔的温度较低.由于声音在空气中传播时总爱拣温度低的路径,所以寺内的钟声会偏向地表,沿地表传向数里外的枫桥河畔.

故答案为:(1)上;(2)2;低;下;较远.

单项选择题

Shopping has always been something of an impulse activity, in which objects that catch our fancy while strolling are immediately bought on a whim. Advertisers and sellers have taken advantage of this fact, carefully positioning inexpensive but attractive items on paths that we are most likely to cross, hoping that our human nature will lead to a greater profit for them. With the dawn of the Internet and its exploding use across the world, the same tactics apply.

Advertisers now place "banners", links to commercial web sites decorated with attractive pictures designed to catch our eyes while browsing the webs, on key web sites with heavy traffic. They pay top dollar for the right, thus creating profits for the hosting web site as well. These actions are performed in the hopes that during the course of our casual and leisurely web surfing, we’ll click on that banner that sparks our interest and thus, in theory, buy the products advertised.

Initial results have been positive. Web sites report a huge inflow of cash, both from the advertisers who tempt customers in with the banners and the hosting web sites, which are paid for allowing the banners to be put in place. As trust and confidence in Internet buying increases and information security is heightened with new technology, the volume of buying is increasing, leading to even greater profits.

The current situation, however, is not quite as optimistic. Just as magazine readers tend to unconsciously ignore advertisements in their favorite periodicals, web browsers are beginning to allow banners to slip their notice as well. Internet users respond to the flood of banners by viewing them as annoyances, a negative image that is hurting sales, since users are now less reluctant to click on those banners, preferring not to support the system that puts them in place. If Internet advertising is to continue to be a viable and profitable business practice, new methods will need to be considered to reinvigorate the industry.

With the recent depression in the technology sector and slowing economy, even new practices may not do the trick. As consumers are saving more and frequenting traditional real estate businesses over their Internet counterparts, the fate of Internet business is called into question. The coming years will be the only reliable indication of whether shopping on the World Wide Web is the wave of the future or simply an impulse activity whose whim has passed. (404 words)

Notes: on a whim 心血来潮。surf v.冲浪。in theory在理论上,顺理成章。hosting 访问率离的。call...into question 质疑,对……提出疑问。

It can be learned from the first paragraph that Internet advertising()

A. has taken the place of more traditional methods of advertising

B. is one of the most effective ways to make profits on the web

C. is paralleling advertising methods in traditional business settings

D. seeks to tempt customers through impulse shopping methods

单项选择题