问题 单项选择题

将盛有一定浓度蔗糖溶液的透析袋口扎紧后浸于蒸馏水中,下图表示透析袋中蔗糖溶液浓度与时间的关系,正确的是()

A.图A

B.图B

C.图C

D.图D

答案

参考答案:B

解析:根据渗透作用的原理,水的跨膜运输特点是从低浓度溶液渗透到高浓度溶液。透析袋中溶液浓度高,能够从蒸馏水中吸水,进而浓度越来越低,所以答案为B。考点:本题考查渗透作用。点评:基础题,水的跨膜运输特点是从低浓度溶液渗透到高浓度溶液,把握此点可以轻松解答。

多项选择题
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