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问题 解答题

从生产的一批螺钉中抽取1000个进行检查，结果有4个是次品，如果从这批螺钉中任取一个螺钉，那么取到次品的概率是多少？

答案

由题意知：一批螺钉中抽取1000个进行检查，结果有4个是次品，

∴从这批螺钉中任取一个螺钉，取到次品的概率是

4
1000
=
1
250
．

单项选择题

关于母乳性黄疸错误的是（）

A.多于生后4～7天出现

B.精神反应、生长发育正常

C.血清胆红素小于342μmol/L

D.2～3周达高峰

E.血清胆红素在停止母乳72小时以上，下降大于或等于50%
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填空题

Exercising to music pumps up brain power


If music makes you smarter, and exercise helps brain function, can exercising to music really boost brainpower Some researchers said it can. Volunteers who listened to Vivaldi’s "Four Seasons" while working out on a treadmill did much better on a test of (1) ability than when they exercised without music, a team (2) Ohio State University found.
"Evidence suggests that exercise improves the (3) performance of people with coronary artery (4) ," said psychologist Charles Emery, who led the study.
"And listening to music is (5) to enhance brainpower. We wanted to put the two results together," Emery (6) in a statement.
Writing in the latest issue of the journal Heart & Lung, Emery and (7) said they studied 33 men and women taking (8) in a cardiac rehabilitation program after having bypass (9) , angioplasty or other procedures to treat clogged arteries.
The (10) said they felt better emotionally and mentally after working out (11) or without the music. But their improvement on the (12) fluency test doubled after listening to music on the treadmills.
"Exercise seems to (13) positive changes in the nervous system, and these changes may have a (14) effect on cognitive ability," Emery said.
"Listening to music may (15) cognitive function through different pathways in the brain. The combination of music (16) exercise may stimulate and increase cognitive arousal (17) helping to organize cognitive output."
Emery said he now wanted to (18) people using music of their own choice. "We used the ’Four Seasons’ because of its (19) tempo and positive effects on medical patients in previous (20) ," Emery said. "But given the range of music preferences among patients, it’s especially important to evaluate the influence of other types of music on cognitive outcomes.\
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