一个样本有100个数据,最大值为7.4,最小值为4.0,如果取组距为0.3,则这

题型:选择题

问题:

一个样本有100个数据,最大值为7.4,最小值为4.0,如果取组距为0.3,则这组数据段分成(  )
A.11组B.12组
C.13组D.以上答案均不对
考点:频数与频率
题型:选择题

已知bg糖水中有ag糖(b>a>0),若再添上mg糖(n>0),则糖水就变甜了,试根据此事提炼一个不等式:(    )。

题型:选择题

公开市场业务是中央银行经常使用的一种重要的一般性的货币政策工具,中央银行进行公开市场操作可以产生的直接效应()。

A.影响商业银行的储备金

B.影响利率水平

C.影响所买卖有价证券的价格和收益率

D.影响公众对一般有价证券的价格和收益率的预期

E.影响社会投资水平

题型:选择题

超声的横向分辨力与下述哪项因素最相关()。

A.超声波长(λ)或频率F.

B.扫描声束

C.探头厚度方向上的声束宽度及其聚焦性能

D.超声脉冲宽度

E.声场的远近及其能量分布

题型:选择题

阅读理解

     Children start out as natural scientists, eager to look into the world around them.Helping them enjoy

science can be easy;there's no need for a lot of scientific terms or expensive lab equipment.You only

have to share your children's curiosity.Firstly, listen to their questions.I once visited a classroom of s

evenyearolds to talk about science as a job.The children asked me" textbook questions" about schooling,

salary and whether I liked my job.When I finished answering,we sat facing one another in silence.Finally I

said, "Now that we're finished with your lists, do you have questions of your own about science?"

      After a long pause, a boy raised his hand, "Have you ever seen a grasshopper(蚱蜢) eat? When I try

eating leaves like that,I get a stomachache.Why?"

     This began a set of questions that lasted nearly two hours.

      Secondly, give them time to think.Studies over the past 30 years have shown that, after asking a

question, adults typically wait only one second or less for an answer,no time for a child to think.When

adults increase their " wait time" to three seconds or more, children give more logical, complete and

creative answers.

      Thirdly, watch your language.Once you have a child involved in a science discussion, don't jump in

with "That's right" or" Very good". These words work well when it comes to encouraging good behavior.

But in talking about science, quick praise can signal that discussion is over.Instead, keep things going by

saying" That's interesting" or" I'd never thought of it that way before", or coming up with more questions or ideas.

     Never push a child to"Think",It doesn't make sense.Children are always thinking, without your telling

them to.What's more, this can turn a conversation into a performance.The child will try to find the answer

you want,in as few words as possible, so that he will be a smaller target for your disagreement.

     Lastly, show; don't tell.Reallife impressions of nature are far more impressive than any lesson children

can learn from a book or a television program.Let children look at their fingertips through a magnifying

glass (放大镜), and they'll understand why you want them to wash before dinner.Rather than saying that

water evaporates (蒸发), set a pot of water to boil and let them watch the water level drop.

1. According to the passage, children are natural scientists, and to raise their interests,the most important

thing for adults to do is________.

A. to let them see the world around

B. to share the children's curiosity

C. to explain difficult phrases about science

D. to supply the children with lab equipment

2. In the last sentence of the first paragraph, the word" lists" could best be replaced by ________.

A. any questions                

B. any problems

C. questions from textbooks    

D. any number of questions

3. According to the passage, children can answer questions in a more logical, complete and creative way if adults________.

A. ask them to answer quickly

B. wait for one or two seconds after a question

C. tell them to answer the next day

D. wait at least for three seconds after a question

4. In which of the following paragraph(s) does the author tell us what to say to encourage children in a science discussion?

A. The second and third.  

B. The fourth and fifth.

C. The fifth and sixth.  

D. The seventh.

题型:选择题

关于体育锻炼对生长发育影响的描述,不正确的是

A.促进肌纤维增长变粗,使身体素质明显改善
B.可促进性发育过早发生,发挥更大的生长潜力
C.有效调节内分泌,使生长激素出现脉冲式分泌
D.是控制体重、调节身体成分的重要手段
E.加速下丘脑对促激素的分泌,加快青春期体格生长

更多题库