求出每个工人平均每天加工多少个零件，填在表格里．甲乙丙加工零件（个）630630

土地最大的自然特性是( )。

A．面积的有限性
B．位置的固定性
C．质量的差异性
D．永续利用的相对性

Cities need to put efforts to deal with pollution and clear the air.

Chinese cities will need to put efforts to clear up the sky when a new department to improve regional air quality is set up by 2015, according to the latest plan released by the State Council．

Besides the existing pollution control program for S02, regional emission caps （区域排放上限） for other certain chemicals will be established in the three key air polluting areas— rhe Yangtze River Delta, Pearl River Delta and the Beijing-Tianjin-Hebei region．Coal-consumption caps will also be tried out in some areas, according to the plan．

The plan is aimed at dealing with regional air pollution—such as acid rain and smog—which have become increasingly obvious in China in recent years and caused a severe threat to people's health, Zhang Lijun, vice-minister of environmental protection, said in an interview on Monday.

The air quality in a city affects the regions nearby because pollutants （污染物）can travel through the atmosphere, said Chai Fahe, vice-director of Chinese Research Academy of Environmental Sciences．

“So efforts to reduce air pollution in a single city, targeting a certain pollutant will not oe enough," Chai said．

Zhang said the country's major industrial districts—the Yangtze River Delta, Pearl River Delta and the Beijing-Tianjin-Hebei region—have recorded more than 100 misty days annually in recent years．

These three regions, home to at least 200 million people, occupy only 6．3 percent of the country's area but consume 40 percent of the country's coal and produce half of its steel, according to official figures．

Studies also show that the visibility （能见度） in eastern regions of China has dropped by 7 to 15 km compared to that in the early 1960s, as a result of air pollution．

Liaoning province, the Shandong Peninsula, Wuhan in Hubei province and its surrounding area, the Changsha-Zhuzhou-Xiangtan region in Hunan province, the Chengdu-Chongqing region, and the western coast of the Taiwan Straits are also listed as areas to carry out such regional air pollution control programs, according to the plan．

The new plan also requires an improved air quality system, which will measure the pollution levels．"The current system, which only measures some major pollutants, cannot reflect the true picture．" said Chai．

小题1:It will not be enough to reduce air pollution in a single city because ______.

A．air pollution has been becoming more and more serious in recent years

B．air pollution like acid rain and smog is threatening people's health

C．air pollutants in a city can travel in the sky and affect nearby areas

D．air pollutants stay in fixed places over the cities小题2:Suppose the visibility in eastern regions of China was 130 km in the early 1960s, the visibility there nowadays is           .

A．123 to 115 km

B．137 to 145 km

C．123 to 145 km

D．115 to 137 km小题3:The main purpose of the passage is        .

A．to inform readers of the damage caused by air pollution

B．to introduce the new plan to control air pollution

C．to provide official figures of air pollution levels

D．to point out the regions affected by air pollution小题4:What does the underlined phrase "the true picture" in the last paragraph mean?

A．The major pollutants．

B．The key polluted areas．

C．The major polluted cities．

D．The pollution levels．

三国东吴造船业发达， 率船对到达__________ 。（今台湾）

有一种沙漠蝎子既没有眼睛，也没有耳朵，它捕食猎物靠的是一种地震仪式的本领，它有八条腿，趴伏时大致对称地放置在躯体四周(如图12所示)，不远处的小虫一有骚动，就会在沙面上引起一阵地震波，蝎子从哪只腿先感到地震波就能判断小虫所在的方向，并从P波和S波到达的时间差就可以“算出”小虫到它的距离。方位和距离都知道了，它就能扑上去捕获小虫了，已知P波速度为150m/s，S波速度为50m/s，如果两波到达沙漠蝎子的时间差为s，则小虫离它的距离多大？

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