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ADSL是一种宽带接入技术，只需路两端加装ADSL设备(专用的Modem)即可实现家庭PC机用户的高速联网。下面关于ADSL的叙述中( )是不正确。
D.它的带宽很高，无论是数据的下载还是上传，传输速度至少在1Mb/s以上

A.它利用普通铜质电话线作为传输介质，成本较低
B.可在同一条电话线上接听、拨打电话并且同时进行数据传输，两者互不影响
C.使用的是专线，用户可以始终处于连线状态

【参考答案】

D
解析：有ADSL速率档次为：512K→1M→2M→4M→全速。
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Without proper planning, tourism can cause problems. For example, too many tourists can(面性)crowd public places that are also enjoyed by the inhabitants 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 (目的地)county 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, airport, air terminals, first-class roads, and other support facilities (设施) 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 lose money.Building a hotel is just a beginning. There must be many support facilities as well, including roads to get to the hotel, electricity, sewers (阴沟) 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.Which do you think has most probably been discussed in the paragraph that goes before this passage?A.It is extremely important to develop tourism.B.Building roads and hotels is essential. (必不可少的)C.Support facilities are highly necessary.D.Planning is of great importance to tourism.
A.B.
C.
Building
D.
Which
E.It
F.
B.Building
G.Support
H.
D.Planning
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