相關(guān)習(xí)題
 0  45043  45051  45057  45061  45067  45069  45073  45079  45081  45087  45093  45097  45099  45103  45109  45111  45117  45121  45123  45127  45129  45133  45135  45137  45138  45139  45141  45142  45143  45145  45147  45151  45153  45157  45159  45163  45169  45171  45177  45181  45183  45187  45193  45199  45201  45207  45211  45213  45219  45223  45229  45237  151629 

科目: 來源: 題型:閱讀理解

Batteries can power anything from small sensors to large systems.While scientists are finding ways to make them smaller but even more powerful, problems can arise when these batteries are much larger and heavier than the devices themselves.University of Missouri(MU) researchers are developing a nuclear energy source that is smaller, lighter and more efficient.

“To provide enough power, we need certain methods with high energy density(密度)”,said Jae Kwon, assistant professor of electrical and computer engineering at MU.“The radioisotope(放射性同位素) battery can provide power density that is much higher than chemical batteries.”

Kwon and his research team have been working on building a small nuclear battery, presently the size and thickness of a penny, intended to power various micro / nanoelectromechanical systems (M/NEMS).Although nuclear batteries can cause concerns, Kwon said they are safe.

“People hear the word ‘nuclear’ and think of something very dangerous,” he said, “However, nuclear power sources have already been safely powering a variety of devices, such as pace-makers, space satellites and underwater systems.”

His new idea is not only in the battery’s size, but also in its semiconductor(半導(dǎo)體).Kwon’s battery uses a liquid semiconductor rather than a solid semiconductor.

“The key part of using a radioactive battery is that when you harvest the energy, part of the radiation energy can damage the lattice structure(晶體結(jié)構(gòu)) of the solid semiconductor,” Kwon said, “By using a liquid semiconductor, we believe we can minimize that problem.”

Together with J.David Robertson, chemistry professor and associate director of the MU Research Reactor, Kwon is working to build and test the battery.In the future, they hope to increase the battery’s power, shrink its size and try with various other materials.Kwon said that battery could be thinner than the thickness of human hair.

67.The text is most probably a ________.

       A.science news report                                  B.book review   

       C.newspaper ad                                           D.science fiction

68.Liquid semiconductor is used to _________.

       A.get rid of the radioactive waste               B.test the power of nuclear batteries.

       C.decrease the size of nuclear batteries          D.reduce the damage to lattice structure.

69.According to Jae Kwon, his nuclear battery _______.

       A.uses a solid semiconductor                         B.will soon replace the present ones.

       C.could be extremely thin                              D.has passed the final test.

70.Jae Kwon gave examples in Paragraph 4_________.

       A.to show chemical batteries are widely applied.

       B.to introduce nuclear batteries can be safely used.

       C.to describe a nuclear-powered system.

       D.to introduce various energy sources.

查看答案和解析>>

科目: 來源: 題型:閱讀理解

One school night this month I walked quietly up to Alexander, my 15-year-old son, and touched his cheek gently in a manner I hoped would seem casual.A year ago he would have ignored this disturbance but now he reacted impatiently and leaned back to his computer screen.

I made a mistake: breaking into my teenager's personal space. “The average teenager has pretty strong feelings about his privacy," Lara Fox and her friend Hilary Frankel told me. Mr.Frankel and Mr.Fox, both 17, are the authors of Breaking the Code, a new book that seeks to bridge the generational divide between parents and adolescents.It is being promoted by its publisher as the first self-help guide by teenagers for their parents, a kind of "Kids Are From Mars, Parents Are From Venus" that explains the language and actions of teenagers.The girls dealt with issues including hanging out late, money, school pressures, smoking etc.

Personally, I welcome their opinions.The most common missteps in interacting with teenagers arise from the war between parents exercising their rights to know what goes on under their roof and teenagers firmly guarding their privacy.Teenagers can be quick to interpret their parents' remarks and respond with anger that masks their vulnerability (脆弱 ). Ms Fox said, "What we want above all is your approval.Don't forget, no matter how much we act as if we don't care what you say, we believe the things you say about us."

Nancy, a New York child-raising expert said she didn't agree with everything the authors suggested but found their arguments reasonable."When your kids are saying, ' You don't get it, and you never will, ' there are lots of ways to respond so that they will listen and that is what the writers point out."

" My parents helped me see that, " Mr.Fox told me, " even though they used to stay out late and ride their bicycles to school, times have changed and the way parents educate children is different.These days there is a major fear factor in bringing up kids.Parents worry about their child crossing the street." The writers said they hoped simply to throw light on teenage thinking.

63.According to the two girls, teenagers nowadays are ____.

       A.independent        B.intelligent     C. inconsiderate           D.sensitive

64.The underlined sentence "You don't get it, and you never will" in the 4th paragraph implies that ____.

       A.the teenagers don't want/to admit their weakness

       B.the teenagers think that their parents will never understand them

       C.the parents do not necessarily force into the world of their children

       D.the generation gap cannot be shortened despite their parents' efforts

65.It can be inferred from the last two paragraphs that ____.

       A.teenagers should guard their privacy

       B.Nancy totally agrees with the two girls' opinions

       C.parents are more concerned about children's safety

       D.the two girls have obtained numerous support from the public

66.Why does the author mention the book "Kids Are From Mars, Parents Are From Venus ?

       A.It is one of the best-sellers.              B.It is also written by the two girls.

       C.The two books have the similar theme.      D.The two books have different opinions.

查看答案和解析>>

科目: 來源: 題型:閱讀理解

My eighth grade consisted of 28 classmates. We knew each other so well that most of us could distinguish each other's handwriting at a glance. Although we grew up together, we still had class outcasts.From second grade on, a small group started harassing (騷擾) two or three of the others.I was one of those two or three, though I didn't know why.In most cases when children get picked on, they aren't good at sports or they read too much or they wear the wrong clothes or they are of a different race.But in my class, we all read too much and didn't know how to play sports.We had also been brought up to carefully respect each other's race.This is what was so strange about my situation.Usually, people are made outcasts because they are in some way different from the larger group.But in my class, large differences did not exist.It was as if the outcasts were invented by the group out of a need for them.

The harassment came in the form of laughter when I talked, and rolled eyes when I turned around.If I was out on the playground and approached a group of people, they often fell silent.Sometimes, someone would not see me coming and I would catch the tail end of a joke at my expense.

There was another girl in our class who was perhaps even more rejected than I.She provided the group with a lot of material for jokes.One day one popular girl came up to me to show me something she said I wouldn't want to miss.We walked to a comer of the playground.Three or four girls there were reading aloud from a small book, which I was told was the girl's diary.

I sat down and, laughing till my sides hurt, heard my voice finally mixed with the others.Often being accepted by others is more satisfying than being accepted by oneself, even though the satisfaction does not last.Looking back, I wonder how I could have participated in making fun of this girl when I knew perfectly well how it felt.If I were in that situation today I would react differently, but I can't honestly be sure.

60.The author was made an outcast because ____.

       A.she couldn't play sports as well as others      B.her classmates needed to find an outcast her

       C.her classmates found her clothes funny      D.family belonged to a minority group

59.How was the author treated as an outcast?

       A.She was refused to approach others.

       B.No one responded to her talking.

       C.She was often the target of teasing.

       D.Her diary was often made public.

61.What did the author do to the girl mentioned in Paragraph 3?

       A.She showed great sympathy with the girl.

       B.She found more materials about the girl for jokes.

       C.She stopped the others from hurting the girl.

       D.She joined others in making fun of the girl.

62.What does the passage intend to tell us?

       A.Everyone is likely to become an outcast.

       B.We shouldn't hit a person when he is down.

       C.Everyone has a desire to be accepted by others.

       D.One should pay somebody back in his own way.

查看答案和解析>>

科目: 來源: 題型:閱讀理解

☆Locks

You have a special card which operates the electronic lock on your room door and a key for the main door of the door of the hotel. These are your responsibility and should never be lent to anyone, including your fellow classmates. If you lose them you will be charged £20 per replacement. Do not leave your room unlocked even for short periods. Unfortunately, theft from student hotels is very common and insurance companies will not pay for stolen goods unless you can prove that your room was broken into by force.

☆Visitors

There are rarely any rooms available for visitors, except at the end of the summer term. Stan Jenkins, the hotel manager, will be able to tell you and can handle the booking. A small charge is made. Stan also keeps a list of local guesthouses, with some information about what they’re like, price, etc. You are also allowed to use empty beds for up to three nights, with the owner’s permission (for example, if the person who shares your room is away for the weekend ), but you must inform Stan before your guest arrives, so that he has an exact record of who’s in the building of a fire breaks out. Students are not allowed to charge each other for this.

☆Kitchens

There is a kitchen on each floor where light meals, drinks, etc. maybe prepared. Each has a large fridge and a food cupboard. All food should be stored, clearly marked with the owner’s name, in one of these two places. Bedrooms are too warm for food to be stored, and the cleaners have instructions to remove any food found in them. After using the kitchen, please be sure you do all your washing up immediately and leave it tidy. If you use it late in the evening, please also take care that you do so quietly in order to avoid disturbing people in nearby bedrooms.

56.If a friend visits you for the weekend, he or she can         .

       A.stay at a local guesthouse

       B.book an empty house for free

       C.use an empty bed without permission

       D.share your room by paying your roommate

57.Which of the following is true according to the passage?

       A.Your insurance will cover what you have lost.

       B.The cleaners will take away food left in the bedrooms.

       C.Spare rooms are least likely to be available in summer.

       D.Students will be fined for lending their cards to others.

58.The passage is probably taken from ____.

       A.a(chǎn) travel guide book                     B.a(chǎn) hotel brochure

       C.a(chǎn) school poster                            D.a(chǎn) club newsletter

查看答案和解析>>

科目: 來源: 題型:

Canada is a large country _____ many people from all over the world live.

        A. which             B. in which           C. that              D. in that 

查看答案和解析>>

科目: 來源: 題型:

  I called the airline to ______ my flight reservation a week before I left for Canada.

    A. expand            B. book              C. confirm           D. strengthen

查看答案和解析>>

科目: 來源: 題型:

33. It was for the first time that the two countries ______ an agreement.

A. reached           B. have reached        C. had reached        D. will reach

查看答案和解析>>

科目: 來源: 題型:

 I have been convinced that the print media are usually more __________ and more reliable than television.  A. actual         B. adequate         C. accurate      D. autonomous

查看答案和解析>>

科目: 來源: 題型:

 The written record of our conversation doesn’t ______ what was actually said. There are a lot of mistakes.A.correspond with   B.relate to       C. compare with      D.communicate with

查看答案和解析>>

科目: 來源: 題型:

 The local government has been accused of not responding _________ to the needs of the homeless in the flood-stricken area.

       A.constantly               B.a(chǎn)ppropriately           C.gradually                D.a(chǎn)pproximately

查看答案和解析>>

同步練習(xí)冊答案