下列光现象中,是由于光的反射形成的是( ) A.从水面上看到水中的“鱼” B.用

题型:选择题

问题:

下列光现象中,是由于光的反射形成的是(  )

A.从水面上看到水中的“鱼”

B.用放大镜看到放大的“字”

C.路灯下人在地面上的“影子”

D.在平面镜前看到镜中的“自己”

考点:光的反射现象
题型:选择题

下列哪项不是支架变形的原因()。

A.支架蜡型变形

B.打磨引起变形

C.包埋料热膨胀不足

D.合金线收缩率过大

E.包埋材料透气性差

题型:选择题

下列程序的输出结果是( )。
#ificlude<iostream>
using namespace std;
int main()

cout.fill('*');
cout.width(5);
cout<<oct<<100<<endl;
return 0;

A.**100

B.**144

C.100**

D.144**

题型:选择题

B

What happens inside the skull of a soccer player when repeatedly heads a soccer ball? That question motivated a challenging new study of the brains of experienced players that has caused discussion and debate among soccer players, and some anxiety among those of us with soccer-playing children.

For the study, researchers at the Albert Einstein College of Medicine in New York selected 34 adults, men and women. All of the volunteers had played soccer since childhood and now competed year-round in adult soccer leagues. Each filled out a detailed questionnaire developed especially for this study to determine how many times they had headed a soccer ball in the previous year, as well as whether they had experienced any known concussions (脑震荡) in the past.

Then the players completed computerized tests of their memory and other learning skills and had their brains scanned, using a complicated new M.R.I. technique which can find structural changes in the brain that can’t be seen during most scans.

According to the data they presented at Radiological Society of North America meeting last month, the researchers found that the players who had headed the ball more than about 1,100 times in the previous 12 months showed significant loss of white matter in parts of their brains involved with memory, attention and the processing of visual information, compared with players who had headed the ball fewer times.

This pattern of white matter loss is “similar to those seen in traumatic (外伤的) brain injury”, like that after a serious concussion, the researchers reported, even though only one of these players was reported to have ever experienced a concussion.

The players who had headed the ball about 1,100 times or more in the past year were also generally worse at recalling lists of words read to them, forgetting or fumbling the words far more often than players who had headed the ball less.

小题1:The passage is most probably a ________.

A.news report

B.research report

C.story for soccer players

D.text for doctors小题2: In which way can researchers find the structural changes in the brain?

A.Computerized test

B.Questionnaire

C.Scanning

D.M.R.I. technique小题3: From the passage we can conclude that frequent heading may have ________.

A.significant effect on brain

B.little effect on one’s brain

C.nothing to do with the brain injury

D.one’s memory improved小题4:What is likely to be the cause of memory loss?

A.Playing soccer frequently

B.Tests of their memory

C.White matter loss

D.Information processing小题5:The underlined word “fumbling” is closest in meaning to ________?

A.remembering

B.misunderstanding

C.recalling

D.missing

题型:选择题

某研究者欲了解2007年某地成年男性的高血压患病情况,抽样调查了200名当地的成年男性,测量并记录其收缩压和舒张压值。

描述该资料的变异程度,宜选用()

A.极差

B.四分位数间距

C.方差

D.标准差

E.变异系数

题型:选择题

痢疾杆菌的主要致病机制是()

A.侵入的细菌数量

B.外毒素

C.神经毒素

D.侵袭力和内毒素

E.肠毒素

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