问题 问答题

某同学要验证电阻的大小与电阻的长度和横截面积有关,他将三根不同的镍铬合金电阻丝R1、R2、R3分别按图所示的电路接在M、N两点间,观察并记录电流表示数,如下表所示:

实验次数电阻丝长度(m)横截面积(m2电流表示数(A)
1R12LS0.3
2R22L2S0.6
3R3LS0.6
(1)分析实验次数1和2,可以验证电阻的大小与电阻的______有关;

(2)分析实验次数1和3,可以验证电阻的大小与电阻的______有关.

答案

(1)分析第1次和第2次的实验数据,可看出此时的材料和长度相同,但横截面积不同,且横截面积越大的电阻越小,因此可以验证电阻的大小与电阻横截面积有关;

(2)分析第1次和第3次的实验数据,可看出此时的材料和横截面积相同,但长度不同,且电阻丝越长电阻越大,因此验证电阻的大小与电阻横截面积有关长度有关.

故答案为:横截面积;长度.

阅读理解

Without proper planning, tourism can cause problems. For example, too many tourists can crowd public places that are also enjoyed by the inhabitants居民of a country. If tourists create too much traffic, the inhabitants become annoyed and unhappy. They begin to dislike tourists and to treat them impolitely. They forget how much tourism can help the country’s economy. It is important to think about the people of a destination country and how tourism affects them. Tourism should help a country keep the customs and beauty that attract tourists. Tourism should also advance the well-being (health and happiness) of local inhabitants.

Too much tourism can be a problem. If tourism grows too quickly people must leave other jobs to work in the tourism industry. This means that other parts of the country’s economy can suffer.

On the other hand, if there is not enough tourism, people can lose jobs. Businesses can also lose money. It costs a great deal of money to build large hotels, airports, air terminals航空集散站, first-class roads and other support facilities needed by tourist attractions. For example, a major international-class tourism hotel can cost as much as 50 thousand dollars per room to build. If this room is not used most of the time, the owners of the hotel will lose money.

Building a hotel is just a beginning. There must be many support facilities设施as well, including roads to get to the hotel, electricity, sewers下水道to handle waste, and water. All of these support facilities cost money. If they are not used because there are not enough tourists, jobs and money are lost.

小题1: Which of the following has most probably been discussed in the paragraph that goes before the passage?

A.It is extremely important to develop tourism.

B.Building roads and hotels is essential.

C.Support facilities are highly necessary.

D.Planning is of great importance to tourism.小题2:Too much tourism can cause all these problems EXCEPT

A.a bad impact on other industries

B.a change of tourists’ customs

C.over crowded of places of interest

D.pressure on traffic小题3:Not enough tourism can lead to

A.an increase of unemployment

B.a decrease in tourist attractions

C.the higher cost of support facilities

D.a rise in price and a fall in pay小题4:It is good for local people to be well aware that tourism will

A.use up large amount of water

B.weaken their economy

C.help establish their traditions

D.help improve their life

阅读理解与欣赏