题目内容
（请给出正确答案）
A.Increases channel utilization, cost ,and interference
B.Increases capacity and cost, but decreases interference
C.Increases capacity, but decreases cost and interference
D.Increases capacity, cost, and interference
E.Increases channel utilization and cost, but decreases interference
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更多“Reusing frequencies in a cellu…”相关的问题
A.Number of carrier frequencies, number of voice channels and available traffic
B.Traffic per person, number of voice channels and available traffic
C.Call loss rate, number of voice channels and available traffic
D.Call loss rate, number of carrier frequencies and available traffic
A.To save antennas
B.To be able to reuse frequencies
C.To share RBS equipment
D.To simplify the installation
E.To share PCM links
A.45 kHz
B.30 MHz
C.45 MHz
D.90 MHz
And we can't even use all of that, because some of it is in the form. of icebergs and glaciers. Even worse, some of it has been polluted.
However, as things stand today, this small amount of fresh water, which is constantly being replaced by rainfall, is still enough for us. But our need_ 3__ water is increasing rapidly – almost day by day. We all have to learn how to stop wasting our previous water. One of the first steps we should _4_ is to develop ways of reusing it.
Experiments have already been done in this__ 5_ but only on a small scale. The systems that have been worked out resemble those used in spacecraft.
A、take
B、or
C、sources
D、for
E、case
One of the most comprehensive ventures was the restoration and transformation of Boston's eighteenth century Faneuil Hall and the Quincy Market, designed in 1824. This section had fallen on hard times, but beginning with the construction of a new city hall immediately adjacent, it has returned to life with the intelligent reuse of these fine old buildings under the design leadership of Benjamin Thomson. He has provided a marvelous setting for dining, shopping, professional offices, and simply walking.
Butler Square, in Minneapolis, exemplifies major changes in its complex of offices, commercial space, and public amenities carved out of a massive pile designed in 1906 as a hardware warehouse. The exciting interior timber structure of the building was highlighted by cutting light courts through the interior and adding large skylights.
San Antonio, Texas, offers an object lesson for numerous other cities combating urban decay. Rather than bringing in the bulldozers, San Antonio's leaders rehabilitated existing structures, while simultaneously cleaning up the San Antonio River, which menders through the business district.
What is the main idea of the passage？
A．During the 1970's, old buildings in many cities were recycled for modern use.
B．Recent interest in ecology issues has led to the cleaning up of many rivers.
C．The San Antoino example shows that bulldozers are not the way to fight urban decay.
D．Strong government support has made adaptive rehabilitation a reality in Boston.
Cell phones operate with radio frequencies,a form. of energy located on the electromagnetic spectrum between FM radio waves and the waves used in microwave ovens,radar,and satellite stations.Cell phones do not emit ionizing radiation,the type that damages DNA and is known to have the ability to cause cancer.
Cell phone technology works on a system of geographically separated zones called"cells".Each cell has its own "base station" that both receives and emits radio waves.When a call is placed from a cell phone,a signal is sent from the cell phone antenna to that cell's base station antenna.The base station responds to the cell phone signal by assigning the phone an available RF channel.When the RF channel is assigned,radio signals are simultaneously received and transmitted,allowing voice information to be carried between the cell phone and the base.The base station transfers the call to a switching centre, where the call can be transferred to a local telephone carrier or another cell phone.
6.There has existed argument about the link between cell phone and brain tumor()
7.The rapid growing number of cell phone users has been a great concern in the US()
8.The 3rd paragraph tries to prove that cell phones do not cause brain cancer()
9.A switching centre is needed when we make a call through cell phone()
10.The topic of the passage is about cell phone and cancer.()
