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     MIT researchers and their colleagues are working tofind out whether energy from trees

can power a network ofsensors(传感器)to prevent spreading forest fires.

     What they learn could also raise the possibility of usingtrees as silent guards along the

nation's borders to discoverpotential threatssuchassmuggled (走私的 ) radioactivematerials.

     The U. S. Forest Service currently predicts and tracksfires with a variety of tools,

including remotc automatcdweather stations. But these stations arc expcnsive andsparsely

(稀疏地) distributed. Additionalsensors could savetrees by providing better local climate

data to be used in fireprediction models and earlier warnings. However,rechargingor

replacing batteries by hand at very hard-to-reach locationsmakes it impractical and costly.

     The new sensor system seeks to avoid this problem bydeveloping trees into a

self-sustaining power supply. Eachsensor is equipped with a battery that can be slowly

recharged using electricity produced by the tree. "A singletree doesn't generate a lot of

power, but over time thetrickle (细流 ) chargeaddsup, justlike '-', saidShuguang Zhang,

one of the researchers on the project andthe associate director of the MIT' s Center for

Biomedica}Engineering( CBE). "

      The system produces enough electricity to allow the temperature and humidity sensors

to wirelessly send outsignals four times a day,or immediately if there's a fire.Each signal

spreads from one sensor to another, until itreaches an existing weather station that sends

the data bysatellite to a forestry command center in Boise,Idaho. Scientists have long

known that trees can produceextremely small amounts of electricity. But no one knew

exactly how the energy was produced or how to takeadvantage of the power.

1. What are the disadvantages of the remote automatedweather stations?

a. They cost too much.

b. They are of poor quality.

c. They are not enough.

d. They can't reach remote places.

A. a,b

B. b,d

C. a,c

D. b,c

2. Which of the following is the best sentence to fill in theblank?

A. Far water does not put out near fire.

B. All rivers run into sea.

C. Many a little makes a miracle.

D. It never rains but it pours.

3. What would be the best title for the passage?

A. Preventing forest fires with tree power

B. Trees can produce electricity

C. Tree power in daily life

D. Developing new energy