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.
a. They cost too much.
b. They are of poor quality.
c. They are not enough.
d. They can"t reach remote places.
B. b,d
C. a,c
D. b,c
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.
B. Trees can produce electricity
C. Tree power in daily life
D. Developing new energy
There is no denying that students should learn something about how computers work, just
as we expect them at least to understand that the internal-combustion engine (内燃机) has
something to do with burning fuel, expanding gases and pistons (活塞) being driven. For
people should have some basic idea of how the things that they use do what they do. Further,
students might be helped by a course that considers the computer"s impact on society. But
that is not what is meant by computer literacy. For computer literacy is not a form of literacy
(读写能力); it is a trade skill that should not be taught as a liberal art.
Learning how to use a computer and learning how to program one are two distinct
activities. A case might be made that the competent citizens of tomorrow should free
themselves from their fear of computers. But this is quite different from saying that all ought
to know how to program one. Leave that to people who have chosen programming as a
career. While programming can be lots of fun, and while our society needs some people
who are experts at it, the same is true of auto repair and violin-making.
Learning how to use a computer is not that difficu1t, and it gets easier all the time as
programs become more "user-friendly". Let us assume that in the future everyone is
going to have to know how to use a computer to be a competent citizen. What does the
phrase "learning to use a computer" mean? It sounds like "learning to drive a car", that is,
it sounds as if there is some set of definite skills that, once acquired, enable one to use a
computer.
In fact, "learning to use a computer" is much more like "learning to play a game", but
learning the rules of one game may not he1p you play a second game, whose rules may
not be the same. There is no such a thing as teaching someone how to use a computer.
One can only teach people to use this or that program and generally that is easily accomplished.
B. be aware of how the things that they use do what they do
C. learn to use a computer by acquiring a certain set of skills
D. understand that programming a computer is more essential than repairing a car.
B. our society needs experts in different fields
C. violin-making requires as much skill as computer programming
D. people who can use a computer don"t necessarily have to know computer programming
B. programs are designed to be convenient to users
C. programming is becoming easier and easier
D. programs are becoming readily available to computer users
B. the fundamentals of computer science
C. specific programs
D. general principles of programming
B. to explain the concept of computer literacy
C. to illustrate the requirements for being competent citizens of tomorrow
D. to emphasize that computer programming is an interesting and challenging job.
scientists: the feathered navigators follow the roads just like we do.
Scientists now believe the phrase "as the crow (乌鸦) flies" no longer means the shortest most
direct route between two points. They say it is likely that crows and other day birds also choose
AA-suggested routes, even though it makes their journeys longer.
Scientists at Oxford University spent 10 years studying homing pigeons using global positioning
satellite (GPS) and got a surprising result. The birds often don"t use the sun to decide their directions.
Instead they fly along motorways, turn at crossing and even go around roundabouts (绕道) , adding
miles to their journeys.
"It really has knocked our research team sideways to find that after a decade-long international
study, pigeons appear to ignore their inbuilt directional instincts (本能) and follow the road system,"
said Prof Tim Guilford, reader in animal behavior at Oxford University"s Department of Zoology.
Guilford said pigeons use their own navigational system (导航系统) when doing long distance trips
or when a bird does a journey for the first time.
"But once homing pigeons have flown a journey more than once, they can fly home on a habitual
route, much as we do when we are driving or walking home from work," said Guilford.
"In short, it looks like it is mentally easier for a bird to fly down a road. They are just making their
journey as simpl e as possible."
B. Why Pigeons Can Fly long Distance?
C. How Pigeons Find Their Ways Home?
D. Why Crows Fly the Shortest Distance?
B. The crows.
C. Day birds.
D. Animals that can fly.
B. by the sun
C. by the road system
D. by following other birds
B. Because their own navigational system doesn"t work.
C. Because it is too hard to use their own navigational system.
D. Because it is easier to make journey simple by following road system.
flesh and blood but also of time. They were
__1__ to show that we all have 6"a body clock" 2__ us. which controls the 3_ and fall of our
body energies, 4_ us different from one day to the next.
The 5 _ 0f "a body clock" should not be too 6 _ since the lives of most living things are controlled
7 the 24-hour night-and-day cycle. We feel 8 and fall asleep at night and become 9__ and
energetic during the day.lf the
24-hour-cycle is _10 , most people experience unpleasant 11 .For example, people who are not 12
to working at night can find that 13__ of sleep causes them to 14 _ badly at work.
15 the daily cycle of sleeping and 16 , we also have other cycles which 17 longer than one day.
Most of us would 18 that we feel good on some days and not so good on 19 ; sometimes our ideas
seem to flow and at other times, they _20__ do not exist.
( ) 2. A.inside
( ) 3. A. movement
( ) 4 A. showing
( ) 5. A. invention
( ) 6. A. difficult
( ) 7. A. from
( ) 8. A. dull
( ) 9. A. regular
( )10. A. disturbed
( )11. A. moments
( )12. A. prevented
( )13. A. miss
( )14. A. perform
( )15. A. With
( )16. A. working
( )17. A. repeat
( )18. A. agree
( )19. A. other
( )20. A.just
B. around
B. supply
B. treating
B. opinion
B. exciting
B. by
B. tired
B. excited
B. shortened
B. feelings
B. allowed
B. none
B. show
B. As well as
B. moving
B. remain
B. believe
B. the other
B. only
C. between
C. use
C. making
C. story
C. surprising
C. over
C. dreamy
C. lively
C. rested
C. senses
C. expected
C. lack
C. manage
C. Except
C.living
C. last
C. realize
C. all other
C. still
D. on
D. rise
D. changing
D. idea
D. interesting
D. During
D. peaceful
D. clear
D. troubled
D. effects
D. used
D. need
D. control
D. Rather than
D. waking
D. happen
D. allow
D. others
D. yet
To learn with your classmates is important in learning process.
At the b________I thought that learning was
none of others" business.I kept telling myself the truth
________the harder you study, the better grade
you get.________(遗憾), the truth seemed no
truth to me.It doesn"t w________ on all exams of
mine.No matter how hard I worked, I still
________(不及格). Each time I didn"t pass the
exam, I thought I hadn"t studied hard e________for
it.The situation didn"t look up________my
teacher suggested I should learn with my classmates.One day I
came a________a difficult problem.Keeping my
teacher"s advice in________, I turned to one of my
classmates for help and solved it________(顺利).
vacations, it can be a challenge to find time for learning.But kids" reading skills don"t have to grow cold
once school"s out.Here are some ways to make reading a natural part of their summer fun:
Explore your library.Visit your local library to check out books and magazines that your kids haven"t
seen before.Many libraries have summer reading programs, book clubs, and reading contests for even
the youngest borrowers.With a new library card, a child will feel extra grownup checking out books.
Read on the road.Going on a long car trip?Make sure the back seat is stocked with favorite reads.
When you"re not at the wheel, read the books aloud.Get some audiobooks (many libraries have large
selections) and listen to them together during driving time.
Make your own books.Pick one of your family"s favorite parts of summer-whether it"s baseball, ice
cream, or the pool-and have your child draw pictures of it or cut out pictures from magazines.Stick the
pictures onto paper to make a booklet and write text for it.When you"re done, read the book together.
Reread it whenever you like!
Keep in touch.Kids don"t have to go away to write about summer vacation.Even if your family stays
home, they can send postcards to tell friends and relatives about their adventures.Ask a relative to be
your child"s pen pal and encourage them to write each week.
Keep up the reading habits.Even if everything else changes during the summer, keep up the reading
routines around your house.Read with your kids every day-whether it"s just before bedtime or under a
shady tree on a lazy afternoon.And don"t forget to take a book to the beach!Just_brush_the_sand_off_
the_pages-it"s_no_sweat!
1. The purpose of the passage is to________.
A. encourage parents to read
B. give advice on raising kids
C. raise a good summer reader
D. suggest places for vacations
2. If you drive on a long trip in summer, you can________.
A. visit the local library and join book clubs
B. borrow some audiobooks to listen to
C. keep in touch with friends by sending postcards
D. read your own picture books with your son
3. By saying "Just brush the sand off the pages-it"s no sweat", the author means________.
A. taking away the sand on the book is very difficult
B. a special book is needed when you"re reading on the beach
C. one can remove the sand on the book with a brush easily
D. there"s no trouble reading even on the beach
4. Who are the intended readers of the passage?
A. Parents.
B. Students.
C. Teachers.
D. Editors.
- 1噬菌体侵染细菌的实验所能证实的DNA是遗传物质的特点是 ①分子结构具有相对的稳定性 ②能够控制蛋白质的合成,从而控制新陈
- 2两手分别拿着一个小木块和一个大石块,把它们都浸没到水中,同时松开手,小木块上浮,大石块下沉,受到浮力大的是(友情提示:由
- 3某同学希望通过比较电路中不同位置的电流表的读数来研究串联电路的电流规律.所接电路图如图1所示,闭合开关后,两电流表指针偏
- 42013年12月2日,搭载着嫦娥三号的长征三号乙运载火箭在西昌卫星发射中心成功发射升空。嫦娥三号发射过程中,世界从中国人
- 5比较阅读[甲][乙]两个文段,完成下面问题。(16分)[甲]鱼,我所欲也,熊掌,亦我所欲也,二者不可得兼,舍鱼而取熊掌者
- 6由阿伏加德罗常数和一个水分子的质量、一个水分子的体积,不能确定的物理量是( )A.水的摩尔质量B.1mol水蒸气的质量
- 7One Saturday afternoon, my daughter Alice asked me, “Are all
- 8在下列四个实验现象中,能说明声音产生所需条件的是( )A.放在钟罩内的闹钟正在响铃,把钟罩内的空气抽去一些后,铃声明显
- 9下列各数中:0.•1,π2,0.1010010001,227,2.3030030003…(相邻的两个3之间的0的个数相差
- 10书面表达。假如你是一名高中生李华,你校大门口有一条街,两边是商店、饭店,每当上下班时他们总是占路摆摊,影响交通和环境。请
- 1小林每天下午5点放学时,爸爸总是从家开车按时到达学校接他回家,有一天学校提前一个小时放学,小林自己步行回家,在途中遇到开
- 2It was for a lifetime of unselfish work among the sick nativ
- 3已知某温度时CH3COOH的电离平衡常数为K.该温度下向20mL0.1mol/LCH3COOH溶液中逐滴加入0.1mol
- 4下列句子中没有语病的一项是(2 分)A.各级政府积极采取措施,加强校园安保,防止校园安全事故不再发生。B.在阅读名著的过
- 5人的生命独特性突出表现在 A.人类会用语言进行交流B.人类会制造和使用工具C.人类的生命最具有智慧D.人类可以统
- 61体积某气态烃和2体积氯化氢发生加成反应后,最多还能和6体积氯气发生取代反应。由此可以断定原气态烃是(气体体积均在相同条
- 7淀粉、蛋白质和脂肪经过消化后的最终产物是( )A.水、无机盐、维生素B.麦芽糖、蛋白块、脂肪微粒C.无机盐、维生素、食
- 8以出产滩羊和枸杞远近闻名的“塞上江南”是[ ]A.湟水谷地B.银川平原C.河西走廊D.河套平原
- 9把图中硬纸沿虚线折起,可得一个正方体,那么这个正方体有数字3的面对着有( )的面。
- 10考古是研究历史的重要途径,可以印证历史上的文字记载。考古工作者曾在湖北省云梦县秦汉古墓中出土了大量秦代竹简,其中一些竹简