如图所示,处在磁感应强度为B的匀强磁场中的单匝矩线圈abcd,以恒定的角速度ω绕

题型:选择题

问题:

如图所示,处在磁感应强度为B的匀强磁场中的单匝矩线圈abcd,以恒定的角速度ω绕ab边转动,磁场方向垂直于纸面向里,线圈所围面积为S,线圈导线的总电阻为R.t=0时刻线圈平面与纸面重合,且cd边正在离开纸面向外运动.则正确的是(  )

A.时刻t线圈中电流的瞬时值icosωt

B.线圈中电流的有效值I

C.线圈中电流的有效值I=

D.线圈消耗的电功率P

考点:正弦式交变电流交变电流的周期和频率
题型:选择题
What a busy day! The three boys were fed, bathed and changed into their nightclothes.Mary had ____ them a story and finally they were asleep.“Babysitting(照看)the three boys aged eight, six and four is extremely ____,” she thought.
“Sleep,” she considered, “if only I could!” But she had difficult homework to complete.Leaning back, she ____ her feet onto the sofa to get comfortable.Whoever said babysitting was a(an) ____ way to make money obviously hadn't met the three boys, she thought.The television was on, the room was warm, and the lights were dim.Mary's ____ felt heavier and heavier.I mustn't sleep, she thought — which was ____ what she did, of course.
Strangely enough, she soon ___ that she was a worldfamous chef(主厨).She made a ____ and wore diamonds and designer clothes.Most days she relaxed by the pool, meeting the rich and famous or ____ — her favorite hobby.She ____ took the leading role in her own TV show.
That is, until she became too ____.“I am definitely the best in the world,” she thought, as she prepared a tasty chicken dish.But ___ seemed to go right.She spilt the flour, she dropped an egg and she cut her finger.Despite all the troubles,  she ____ to get the chicken into the dove.Soon, smoke blanketed the room.The chicken was on fire.____ set in, but Mary could not run — she was ____ to the spot.She tried hard to move, but could not, ____ a sharp sound awoke her.
She got shocked and confused — ____ was pouring from the kitchen.Rushing to investigate, she was met by three ____ little faces and some very burnt bread.“Sorry, we were hungry and you were ____, so we tried to make some bread,” explained a boy.Relieved, Mary made them a snack and sent them back to bed.She____ them never to fall asleep on the job again!
小题1:
A.givenB.writtenC.toldD.taught
小题2:
A.successfulB.helpfulC.tiringD.surprising
小题3:
A.shookB.putC.bentD.kept
小题4:
A.difficultB.boringC.importantD.easy
小题5:
A.eyesB.mindC.heartD.legs
小题6:
A.nicelyB.exactlyC.curiouslyD.carelessly
小题7:
A.realizedB.remindedC.learntD.dreamt
小题8:
A.decisionB.fortuneC.businessD.plan
小题9:
A.cookingB.readingC.runningD.babysitting
小题10:
A.justB.everC.evenD.only
小题11:
A.selfishB.proudC.stubbornD.sensitive
小题12:A everything     B.something       C.anything    D.nothing
小题13:
A.triedB.arrangedC.managedD.prepared
小题14:
A.PanicB.PainC.NoiseD.Stress
小题15:
A.frozenB.draggedC.pushedD.brought
小题16:
A.becauseB.untilC.asD.unless
小题17:
A.smokeB.lightC.waterD.fire
小题18:
A.cheerfulB.strangeC.guiltyD.confident
小题19:
A.busyB.hungryC.worriedD.asleep
小题20:
A.promisedB.allowedC.expectedD.persuaded
题型:选择题

下列不能解除植物顶端优势的措施是:

A.去掉顶芽

B.在去掉顶芽的断口处放一块含有生长素的羊毛脂

C.在去掉顶芽的断口处放一块含有细胞分裂素的羊毛脂

D.在去掉顶芽的断口处放上琼脂小块

题型:选择题

生长素对根原基发生的主要作用是()。

A.促进细胞伸长

B.刺激细胞的分裂

C.促进根原基细胞的分化

D.促进细胞扩大

题型:选择题

阅读理解。

     For a writer, there is hardly any greater honor than winning the Nobel Prize for literature.

     And for a woman writer, claiming the prize is even harder, for only eight women once won it. Austria's

Elfriede Jelinek is the ninth and the first since 1996.

     The Stockholm-based Swedish Academy announced last Thursday that Jelinek won this year's Nobel Prize

in literature. She is recognized for her socially critical (批判的) novels and plays.

     Jelinek, 57, made her literary debut (初次露面) in 1967. She has written plays, novels and poetry. She is

best known for her autobiographical 1983 novel"The Piano Teacher", made into a movie in 2001.

     The basic theme of her work is the inability of women to live as people beyond the roles and personalities

traditionally expected of them. Her characters struggle to lead lives not normally acceptable in society. "The

nature of Jelinek's texts is often hard to define. They shift between prose (散文) and poetry and songs, they

contain theatrical scenes and film script," said the academy.

     The Nobel Prize was founded by Swedish inventor Alfred Nobel. Nobel died in 1896 and left his fortune

of about US $920 million to a fund to honor people who have helped other human beings. This year each prize

is worth US $13 million.

1. The underlined word "them" in the last second paragraph refers to _____.

A. roles

B. people

C. texts

D. women

2. Elfrede Jelinek won the Nobel Prize just because _____.

A. she was an Austrian woman writer

B. she wrote socially critical novels and plays

C. her novel "The Piano Teacher" was made into a movie

D. the nature of her texts is hard to define.

3. Which of the following about the Nobel Prize is TRUE?

A. It is harder for a woman writer to win than a man writer.

B. The total prize every year was $920 million.

C. Women writers were not awarded until 1996.

D. Only eight women writers won the prize since 1996.

4. This passage is most likely taken from _____.

A. a travel magazine

B. a history book

C. a newspaper

D. an advertisement

题型:选择题

在化工生产中,物料的状态和性质发生变化,但物料的质量并不改变,这个规律就称作()定律。

A.能量守恒

B.质量守恒

C.动量守恒

D.物质不灭

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