问题 单项选择题

以下会使离心压缩机发生喘振现象的工况是()。

A、流量减少

B、进气温度降低

C、流量增加

D、以上全会

答案

参考答案:A

单项选择题
阅读理解

阅读下面的短文,并根据短文后的要求答题。(请注意问题后的词数要求)

     [1]It seems parents have long been right. Going to bed early is key to getting enough sleep and helping

adolescents feel on top of the world, a new study reported.

     [2]A lack of sleep among youngsters may trigger depression and suicidal thoughts, according to the

study by the Columbia University Medical Center.

     [3]"Our results are consistent with the theory that inadequate sleep is a risk factor for depression, working

with other risk and protective factors through multiple possible causal ways to the development of this mood

disorder," said lead author James Gangwisch.

     [4]"Adequate quality sleep could therefore be a preventative measure against depression and a treatment

for depression," he added in the study published in the Friday issue of Sleep magazine.

     [5]The study followed the nightly habits of some 15,659 college and high-school students, and found those

who consistently turned in after midnight had a 24 percent higher risk of depression than those who _______ 

before 10:00 pm. Night owls also ran a 20 percent higher risk of battling suicidal thoughts, the study added.

     [6]The American Academy of Sleep Medicine recommends that adolescents should sleep at least nine hours

or more a night. Those who were tucked in before 10:00 pm reported they slept on average about eight hours

and 10 minutes. But that amount of sleep dropped significantly for those in bed after midnight.

     [7]And adolescents who slept five hours or less a night were 71 percent more likely to suffer depression

and 48 percent more at risk of becoming suicidal, the study said.

     [8]"It is a common perception and societal expectation that adolescents do not need as much sleep as pre-

adolescents. Yet studies suggest that adolescents may actually require more sleep." said Gangwisch.

     [9]"Studies have found that adolescents do not go to bed early enough to make up for earlier school start

time. And transitions to earlier school start times have been shown to be associated with significant sleep

deprivation."

1. What's the main idea of the passage? (Please answer within 8 words)

    _____________________________________________________________________________________

2. What theory are the study results similar to? (Please answer within 20 words)

    _____________________________________________________________________________________

3. Fill in the blank in Paragraph 5 with proper words. (Please answer within 6 words)

    _____________________________________________________________________________________

4. Which sentence in the text is the closest in meaning to the following one? It's widely accepted that the

    youngsters needn't sleep as much as the child. 

    _____________________________________________________________________________________

5. Translate the underlined sentence in Paragraph 9 into Chinese. 

    _____________________________________________________________________________________