关于B-DNA双螺旋结构的叙述不正确的是（）。 A.遵循碱基互补规则，但有摆动现象

发布时间：2017-08-22 21:03 │ 来源：www.tikuol.com

题型：单项选择题 A1/A2型题

问题：

关于B-DNA双螺旋结构的叙述不正确的是（）。

A.遵循碱基互补规则，但有摆动现象

B.戊糖磷酸在螺旋外侧、碱基在内侧

C.每个螺旋为10个碱基对

D.通过碱基之间的氢键维系稳定

E.双螺旋的两条链是反向平行的

考点：病理学技术（师）分子生物学分子生物学题库

题型：单项选择题 A1/A2型题

完形填空.

     Can you really travel around the world for free? Li Jun, a 17-year-old girl from Shenzhen Foreign
Language School, still can't __1__ her l0-day free training camp in the Alps in Switzerland last month
was true !
     But __2__ did she achieve this once-in-a-lifetime opportunity ?
     Last October, a piece of short world __3__ in a newspaper "Have a chance to see the world, for
free", caught her eyes. When she asked her friends if the story was __4__, they laughed at her, for they
thought she was day-dreaming. However, Li decided to apply (申请) on-line the following weekend.
"Opportunity is everywhere. I'd like to keep my eyes open and catch the chance." she told herself.
What happened next was tests on health, hobbies and awareness (意识) of environmental protection.
She __5__ all of them very easily.
     On December 14, Li Jun surprised her friends with an invitation letter from the program, the Pangaea
Young Explorer Selection Camp __6__ by South African explorer Mike Horn.
     __7__ January 11, Li left for Switzerland, with several newly bought ski-suits in her suitcase. Over the
next week, she and 15 other teenagers from around the world  __8__ exciting training and lessons. They
took day-trips up the Alps to an altitude (纬度) of 3,200  meters, went sledging (滑雪橇) at night using
modern equipment. They were also encouraged __9__ difficult journeys up mountains, down hills, and
through forests.
     Because of her performance during the training, Li was chosen as one of the eight young __10__ to join Mike Horn in the South Island of New Zealand in May. She will write for the newspaper and share her
fun experiences there with readers.

( ) 1. A. realize
( ) 2. A. how
( ) 3. A. news
( ) 4. A. really
( ) 5. A. went
( ) 6. A. set
( ) 7. A. On
( ) 8. A. joined
( ) 9. A. complete
( ) 10. A. readers

B. think
B. why
B. method
B. truly
B. past
B. started
B. In
B. took part
B. to complete
B. explorers

C. believe
C.when
C. problem
C. real
C. failed
C. begun
C. At
C. attended
C. completing
C. writers

D. hope
D. what
D. advice
D. true
D. passed
D. run
D. Until
D. took part in
D. completes
D. reporters

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采煤工作面在掘进完成后，不需经过验收就可以直接生产。

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什么是溢缴款？

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患者男性，30岁。左侧胸痛4个月，下肢无力2个月。神经系统查体：左下肢肌力4级，右下肢肌力5级（-）。右侧T₁₀以下痛温觉消失，左侧减退。T₄水平痛觉过敏。左侧巴氏征阳性。

考虑诊断为（）

A.脊髓炎

B.脊髓髓内肿瘤

C.脊髓髓外硬膜下肿瘤

D.脊髓硬膜外肿瘤

E.心绞痛

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