一根弹簧的下端挂一重物,上端用手牵引使重物向上做匀速直线运动.从手突然停止到物体

题型:选择题

问题:

一根弹簧的下端挂一重物,上端用手牵引使重物向上做匀速直线运动.从手突然停止到物体上升到最高点时止.在此过程中,重物的加速度的数值将(  )

A.逐渐增大

B.逐渐减小

C.先减小后增大

D.先增大再减小

考点:牛顿第二定律
题型:选择题

美国和日本是环太平洋地区的两个大国,下列与两国关系的发展演变直接相关的事件有:

①《九国公约》②波茨坦公告③马歇尔计划④珍珠港事件[ ]

A.①②③

B.①③④

C.②③④

D.①②④

题型:选择题

对三尖瓣闭合不全时产生的杂音,描述正确的是()

A.在左侧听诊最清楚

B.心外性杂音

C.机能性杂音

D.产生颈静脉阴性波动

E.缩期杂音

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Making an advertisement for television often costs more than a movie. For example, a two – hour movie costs $6 million to make. A TV commercial can cost more than $6 000 a second. And that does not include cost of paying for air time. Which is more valuable, the program or the ad? In terms of money – and making money is what television is all about – the commercial is by far the more important.

Research, market testing, talent, time and money —— all come together to make us want to buy a product.

No matter how bad we think a commercial is, it works. The sales of Charm went up once the ads began. TV commercials actually buy their way into our head. We, in turn, buy the product.

And the ads work because so much time and attention are given to them. Here are some rules of commercial ad making. If you want to get the low middle – class buyer, make sure the announcer has a though, manly voice. Put some people in the ad who work with their hands. If you want to sell to upper – class audience, make sure that the house,  the furniture, and the hair style are the types that the group identifies  with. If you want the buyer feel superior to the character selling the product, then make that person so stupid or silly that everyone will feel great about himself or herself.

We laugh at commercials. We don’t think we pay that much attention to them. But evidence shows we are kidding ourselves. The making of a commercial that costs so much money is not kid stuff. It’s big, big business. And it’s telling us what to think , what we need, and what to buy. To put simply, the TV commercial is a form of brainwashing.

小题1:TV commercials are more important than other programs to television because      .

A.they bring in great profits

B.they require a lot of money to make

C.they are not difficult to produce

D.they attract more viewers than other programs小题2:The purpose of all the efforts made in turning out TV commercials is         .`

A.to persuade people to buy the product

B.to show how valuable the product is

C.to test the market value of the product

D.to make them as interesting as TV movies小题3:From the rules set for making commercial ads, we can see that         .

A.the lower – middle – class buyer likes to work with his hand

B.the more stupid the characters, the more buyers of the product

C.ad designers attract different people with different skills

D.an upper – class buyer is only interested in houses and furniture小题4:It is believed by the writer that         .

A.few people like to watch TV commercials

B.TV commercials are a good guide to buyers

C.TV commercials often make people laugh

D.people do not think highly of TV commercials小题5:What does the author actually mean in the last paragraph?

A.He asks TV viewers never to laugh at the TV commercial ads.

B.Commercials are used to show the true value of a product to be sold.

C.TV commercials cost much and they do influence us in one way or another.

D.Brainwashing must be introduced to sell something on TV.

题型:选择题

去除尾气中重金属污染物质的机理是什么?

题型:选择题

电机车轮轮心采用()材料。

A、铸铁

B、优质钢

C、碳素钢

D、合金钢

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