第二课时: Section A: 2a, 2b, 2c. What’s his name? His name is- What’s her name? Her name is- 查看更多

 

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(10分)植物具有向重力生长的特性,下列是研究根向重力生长机理的两个实验。
实验一:将空白琼脂和含EDTA的琼脂做成帽状,分别套在甲、乙两组玉米胚根的根冠外(示意图如下)。提示:EDTA的作用是去除与其临接部位的 Ca2+

将胚根水平放置培养一定时间后,观察到甲组胚根向重力(下)生长,乙组胚根水平生长。根据上述实验结果,得出实验结论:                               
  实验二:水平放置的胚根弯曲向下生长,与根冠近地侧的Ca2+浓度明显高于远地侧有关。研究表明,根总是朝着Ca 2+浓度高的方向弯曲生长。为验证这一结论,有人设计了下列实验方案。请根据提供的实验材料和用具,写出第二步及以后的实验步骤和实验结果,并回答问题。
(1)实验材料和用具:胚根等长的萌发玉米种子,空白琼脂帽,含EDTA的琼脂帽,上面部分含Ca2+的琼脂帽(水平方向),培养皿等。
(2)实验步骤:
  第一步:取若干个培养皿,在每个培养皿中放置适量的萌发玉米种子,按实验一中乙组的方法处理胚根一定时间后,移去根冠外的琼脂帽。然后将培养皿平均分成两组,编号为 A组、B 组。 
  第二步:                                                            
  第三步:                                                            
(3)实验结果:                                                         
(4)科学家进一步证实,根冠中生长素的分布受Ca2+浓度影响,当胚根水平放置时,重力诱导Ca2+向根冠下侧移动,导致近地侧的生长素浓度比远地侧高。请分析胚根的生长素分布与向重力生长的关系:                                  

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  1.由于大雪,飞行员只得把飞机降落到另一座城市的一个飞机场。

   ______________ _____ the snow, the pilot had to land the plane at an airport in another city.

  2.老师不会鼓励学生在考试前才温书至深夜,他们应该上课时专心听讲才对。

   Teachers do not encourage students to pull an all night for exams. They should _____ _______during lessons.

  3.当你遇到问题的时候不要放弃,试试其他方法。

  Don’t _____ _____ when you have a problem, try another way.

  4.她根据遗嘱获得了一大笔财产。

  She bagged a fabulous fortune _________________ _____ the will.

  5.我给你五美元请你帮我看下车。

  I pay you 5 dollars to _____ _________ my car.

  6.我穿了一件红外套以便他能很容易地看见我。

  I put on a red coat _____ _____________he could see me easily.

  7.妇女们带着孩子排队领取食物。

  Women _____ _____ with children for the food.

  8.每早他都骑车载我去上学。

   Every morning he _____ _____ _____ _____ school.

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I am a middle-school student. Now let ___1___ tell you something ___2___ our classroom.
It's very ___3___. There are two maps ___4___ the back wall. ___5___ is a map of China.
___6___ is a map of the world (世界).
There are ___7___ desks and chairs in our classroom. There is a big desk ___8___ the
teacher in the front of it. We ___9___ four classes in the ___10___ and two in the afternoon
1. a. I      b. my        c. me      d. we
2. a. about    b. in        c. on      d. at
3. a. small    b. big       c. bigger    d. biggest
4. a. in      b. on        c. under     d. over
5. a. It      b. It's       c. One      d. one
6. a. Other    b. Others      c. Another    d. The other
7. a. fourty    b. forty      c. forteen    d. fourteenth
8. a. for     b. of       c. to       d. about
9. a. there is   b. there are    c. has      d. have
10. a. moning   b. mourning     c. morning    d. moring

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I am a middle-school student. Now let ___1___ tell you something ___2___ our classroom.

It's very ___3___. There are two maps ___4___ the back wall. ___5___ is a map of China.

___6___ is a map of the world (世界).

    There are ___7___ desks and chairs in our classroom. There is a big desk ___8___ the

teacher in the front of it. We ___9___ four classes in the ___10___ and two in the afternoon

    1. a. I      b. my        c. me      d. we

    2. a. about    b. in        c. on       d. at

    3. a. small     b. big        c. bigger     d. biggest

    4. a. in      b. on        c. under     d. over

    5. a. It      b. It's       c. One      d. one

    6. a. Other     b. Others      c. Another    d. The other

    7. a. fourty    b. forty       c. forteen    d. fourteenth

    8. a. for      b. of        c. to       d. about

    9. a. there is   b. there are     c. has      d. have

    10. a. moning   b. mourning     c. morning    d. moring

 

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A ten-year-old teacher
  How young can a teacher be?  A teacher can be any age. Just ask Chrissie Mckenney. She was only 10 when she started teaching.
   How did Chrissie get the job It was not easy. Chrissie wanted to help children who can't hear. But the school had never had such a young helper. Could Chrissie do it
First, Chrissie learned to sign. Signing is a way of talking with your hands. Soon it was easy for Chrissie to talk to the children. So the school let her help. Now Chrissie visits the school almost every day. The children love their young teacher. She is their friend.
【小题1】Chrissie wanted to help children who can't______.
A. hear         B. See             C. play
【小题2】This story tells about a______.
A. special class    B. young teacher      C. silly person
【小题3】In the third part of the story, what does the word "sign" mean______
A.看    B. 手势         C. 听
【小题4】The school let Chrissie help because she ____.
A. was too old         B. could sign      C. could not hear
【小题5】You can guess from the story that most teachers ______Chrissie.
A. are older than     B. do not like       C. are just like

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