问题 选择题

下列作图正确的是[ ]

 A.杠杆的力臂

答案

答案:C

题目分析:

A、力臂等于支点到力的作用线的距离,只有当力与直杠杆垂直时,力臂才等于支点到力的作用点的距离,故A错误;
B、平面镜所成像与成像物体的对应点连线与平面镜垂直,且像和成像物体到平面镜的距离相等,图中像和成像物体的位置不对,故B错误;
C、螺线管中电流方向向上,由安培定则可知左侧为N极,磁感线由N极出发会的S极,磁极间异名磁极相互吸引,所以小磁针的N极指向右侧,故C正确;
D、使用滑轮组时,有几股绳子吊着物体,拉力就是物重的几分之一,图中绳子股数是4,拉力应为G的四分之一,故D错误.
故选:C.

阅读理解

阅读理解

     In a world with limited land,water and other natural resources,the harm from the traditional business

model is on the rise.Actually,the past decade has seen more and more forests disappearing and the globe

becoming increasingly warm.People now realize that this unhealthy situation must be changed,and that we must be able to develop in sustainable ways.That means growth with low carbon or development of

sustainable products.In other words,we should keep the earth healthy while using its supply of natural

resources.

     Today,sustainable development is a popular trend in many countries.According to a recent study,the

global market for lowcarbon energy will become three times bigger over the next decade.China,for

example,has set its mind on leading that market,hoping to seize chances in the new round of the global

energy revolution.It is now trying hard to make full use of wind and solar energy,and is spending a huge

amount of money making electric cars and highspeed trains.In addition,we are also seeing great growth in

the global markets for sustainable products such as palm oil,which is produced without cutting down

valuable rainforest.In recent years the markets for sustainable products have grown by more than 50%.

     Governments can fully develop the potential of these new markets.First,they can set high targets for

reducing carbon emissions (排放) and targets for saving and reusing energy.Besides,stronger arrangement of public resources like forests can also help to speed up the development.Finally,governments can avoid

the huge expenses that are taking us in the wrong direction,and redirecting some of those expenses can

accelerate the change from traditional model to a sustainable one.

     The major challenge of this century is to find ways to meet the needs of a growing population within the limits of this single planet.That is no small task,but it offers abundant new chances for sustainable product

industries.

1. The traditional business model is harmful because of all the following EXCEPT that  ________.

A. it makes the world warmer

B. it consumes natural resources

C. it brings severe damage to forests

D. it makes growth hard to continue

2. What can we infer from Paragraph 2?

A. China lacks wind and solar energy.

B. China is the leader of the lowcarbon market.

C. Highspeed trains are a lowcarbon development.

D. Palm oil is made at the cost of valuable forests.

3. To full develop the lowcarbon markets,,government can ________.

A. cut public expenses

B. forbid carbon emission

C. develop public resources

D. encourage energy conservation

4. We can learn from the last paragraph that businesses have many chances to ________.

A. develop sustainable products

B. explore new natural resources

C. make full use of natural resources

D. deal with the major challenge

5. What is the main purpose of the passage?

A. To introduce a new business model.

B. To compare two business models.

C. To predict a change of the global market.

D. To advocate sustainable development.

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