纤维粉尘是指纵横径之比()。A.>10:1 B.>5:1 C.>3:1 D.2:1

题型:单项选择题

问题:

纤维粉尘是指纵横径之比()。

A.>10:1

B.>5:1

C.>3:1

D.<3:1

E.>2:1

考点:公卫执业助理医师公卫执业助理医师题库
题型:单项选择题

 阅读理解。

                                                  Give Water, Save Lives

     A bottle of water may not seem like much to you, but thousands of bottles will be of great help for people

who live in drought-hit (遭受旱灾) areas in China.

     Since last autumn, there has been very little rain in Southwest China. Some places, especially in Yunnan.

Guangxi, Sichuan, Guizhou, have experienced a serious drought. Crops (庄稼) died, the land cracked, and

wells (井) and rivers dried up. More than 20 million people are having difficulty in finding safe drinking water.

     After learning about the drought, many people around the country helped by giving water, money and other

things.

     Last week, every member of the Communist Youth League (共青团员) and Young Pioneers (少先队员)

were encouraged to give one bottle of water to the drought-hit areas. Students in primary schools and middle

schools quickly joined the activity. In Yuhua Primary School in Xi' an, 900 students bought over 1,000 bottles

of water with their pocket money. They also wrote their wishes on the bottles.

    The serious drought has also made students realize the importance of saving water.

     Students from Nanshan Middle School in Huizhou in Guangdong went on the street to tell people to take

part in water-saving activities.

     "I've heard that some children in drought-hit areas don't have enough drinking water. They have to drink

muddy (含有泥土的) water. I feel really sad about that," said one student. "I decide to take a shower twice

a week instead of every day to save water." he said.

1. Why did a serious drought happen in Southwest China?

    ________________________________________________

2. What does the underlined (画线的) word "cracked" probably mean in Chinese? 

    ________________________________________________

3. What did people do after learning about the drought?

    ________________________________________________

4. Is a bottle of water helpful for the people in drought-hit areas? 

    ________________________________________________

5. What can you learn from the passage? 

    ________________________________________________

题型:单项选择题

某实验小组要描绘一个标有“3.6V,1.2W”的小灯泡的伏安特性曲线,所供选择的器材除了导线和开关外,还有以下一些器材可供选择: 电压表V(量程5V,内阻约为5kΩ)直流电源E(电动势4.5V,内阻不计)电流表A1(量程350mA,内阻约为1Ω)电流表A2(量程150mA,内阻约为2Ω)滑动变阻器R1(阻值0 ~ 200Ω)滑动变阻器R2(阻值0 ~ 10Ω)

⑴实验中为较准确测量,电流表应选      ,滑动变阻器应选     (填写器材代号);

(2)在虚线框内画出实验电路图。

(3)由正确实验操作得到的数据描绘出小灯泡的伏安特性曲线如图乙所示,将两个这样的灯泡并联后再与10Ω的定值电阻串联,接在内阻不计电动势为8V的电源上,此时通过定值电阻的电流为  A,每盏灯泡的电阻值为  Ω,每盏灯泡的功率为     W

(保留两位有效数字)

题型:单项选择题

下列物质的分离方法中,是利用密度不同达到分离的是

A.把石油经蒸馏分离成为汽油,煤油和柴油等

B.煎中药时用水在煮沸条件下提取中药的有效成分

C.把大豆磨碎后,用水溶解其中的可溶性成分,经过滤后,分成豆浆和豆渣

D.做饭洗米时淘去米中的沙

题型:单项选择题

热铆的操作过程有哪些?

题型:单项选择题

下列关于出让方式,表述不正确的是( )。

A.土地使用权的协议出让指政府作为土地所有者(出让方)与选定的受让方磋商用地条件及价款.达成协议并签订土地使用权出让合同,无偿出让土地使用权的行为

B.拍卖出让国有建设用地使用权.是指市、县人民政府国土资源行政主管部门发布拍卖公告,由竞买人在指定时间、地点进行公开竞价,根据出价结果确定国有建设用地使用权人的行为

C.招标出让国有建设用地使用权,是指市、县人民政府国土资源行政主管部门发布招标公告,邀请特定或者不特定的自然人、法人和其他组织参加国有建设用地使用权投标,根据投标结果确定国有建设用地使用权人的行为

D.挂牌出让方式不仅具有招标、拍卖的公开、公平、公正的特点,而且具有招标、拍卖不具备的优势,是招标、拍卖方式出让建设用地使用权的重要补充

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