搜题请搜索小程序“爱下问搜题”
问题 单项选择题

泵壳的另一个作用是，由于涡壳的过水断面是( )的，因此它能把液体的大速度水头转化为压头；有时还能起到消除水流回转运动的作用。

A．不光滑
B．不规则
C．各种泵不同
D．逐渐扩大

答案

参考答案：D

阅读理解
阅读理解。
Ask Dr? Jeffers        This month Dr. Jeffers is answering questions about the human
brain and how it works.
Dear Dr. Jeffers,
     One of my colleagues, Felix Moeller, told me that scientists are learning to use computer to 'read
minds'. Is there any truth to this story/
-Jane Leon, New York, USA
Dear Ms. Leon,
     Well, a lot of research is being conducted in this area, but so far, the brain scanning equipment
and corresponding computer programs haven't been able to actually read thoughts. In one experiment,
test subjects (受试者) were connected to scanning equipment and shown two numbers on a screen.
They were then asked to choose between adding or subtracting (减) the two numbers. Using this
method, researchers were able to follow brain processes and make the correct assumptions (假设) 70
percent of the time. It's not quite mind reading, but it's certainly a first step.
-Dr. J.
Dear Dr. Jeffers,
     My three-year-old son loves it when I dig my fingers into his sides and tickle (胳肢) him until he
laughs uncontrollably. The other day I noticed him trying to tickle himself but he couldn't do it. Why
not?
-Glenn Lewis, Vancouver, Canada
Dear Mr. Lewis,
     It's because of how the brain works. The brain is trained to know what to pay attention to and
what to ignore. It causes us to ignore physical feelings we expect to happen, but it causes a mild panic
reaction when there is an unexpected feeling. For example, you don't notice how your shoulder feels
while you're walking down the street. But if someone comes up behind you and touches you lightly on
the shoulder, you may jump in fear. It's that unexpected part that causes the tickle reaction.
-Dr. J.
1. What can we learn from the answer to the first question?
A. Some equipment is able to read human minds.
B. Some progress has been made in mind reading.
C. Test subjects have been used to make decisions.
D. Computer programs can copy brain processes.
2. People laugh when tickled by others because the feeling is _____.
A. unexpected
B. expected
C. comfortable
D. uncomfortable
3. Who has got a little child according to the text?
A. Ms. Leon
B. Mr. Lewis
C. Mr. Moeller
D. Dr. Jeffers
4. According to the text, Jeffers is probably _____. 
A. a computer programmer
B. a test subject
C. a human brain expert
D. a medical doctor
查看答案
问答题 简答题

简述尿液管型形成的机制和条件。
查看答案