大气污染监测，每年采样季节和次数至少是A．春夏两季各一次B．夏秋两季各一次C．冬夏两

某学生管理系统中，教师实体在学籍管理系统中被称为“教师”，而在人事管理系统中被称为“职工”，这类冲突被称为______。

A) 语义冲突
B) 命名冲突
C) 属性冲突
D) 结构冲突

某厂一台600MW机组，2008年3月1日12：37因计划降低出力8.5MW，持续2小时，其余时间全出力运行。该机组当月等效计划降低出力系数是（）。

A、0.03%

B、0

C、0.27%

D、0.3%

阅读理解。

     Scientists say they now have proof to support the old-fashioned advice that it's best to sleep on a problem.

They say sleep strengthens the memory and helps the brain organize the masses of information we receive

each day.

     The lead researcher Bob Stickgold at the Harvard Medical School said, "Sleep helps us draw rules from our

experiences. It's like knowing the difference between dogs and cats even if it's hard to explain."

     The US research team studied how well students remembered connections between words and symbols,

reports New Scientist. They compared how the students performed if they had had a sleep between seeing the

words and having the test, and if they had not slept. They found that people were better able to remember lists

of related words after a night's sleep than after the same time spent awake during the day. They also found it

easier to remember themes that the words had in common. But they forgot around one in four more themes if

they had been awake.

     Prof. John Groeger, University of Survey's Sleep Research Centre, said, "People have been trying for years

to find out what the purpose of sleep is, as we know that only certain parts of it have a restorative (促使康复

的) value."

     "We form and store huge numbers of experiences in the head every day, and sleep seems to be the way the

brain deals with them all."

1. The phrase "to sleep on a problem" in Paragraph l most likely means "_____".

A. to pay full attention to a problem

B. to wait until the next day for a decision

C. to sleep to forget a problem

D. to have difficulty in sleeping

2. In the study by the US research team, students were asked to _____.

A. put together words of similar meanings

B. remember words and their meanings

C. show their knowledge of words

D. make up lists of related words

3. Which of the following may be easier to remember?

A. Themes learned right before the test.

B. Rules from personal experiences.

C. Words learned before a good sleep.

D. Ideas stored together in the brain.

4. What may be the importance of the research?

A. It shows that sleep may help us manage information.

B. It helps find out the common themes of words.

C. It tells us that more sleep can improve health.

D. It proves the value of old-fashioned advice.

直流弧焊发电机是由一台（）和一台（）组成。

照明变压器可提供安全电压。