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硅钼黄光度法测定水中溶性二氧化硅时，哪些物质会干扰测定？如何消除干扰？

答案

参考答案：

（1）色度及浊度干扰测定，可以采用补偿法（不加钼酸铵的水样为参比）予以消除。

（2）丹宁、大量的铁、硫化物和磷酸盐干扰测定，加入草酸能消除或降低其干扰。

（3）在方法规定的条件下，加入草酸（3mg/ml），样品中含铁20mg/L，硫化物10mg/L、磷酸盐0.8mg/L，丹宁酸30mg/L以下时，不干扰测定。

单项选择题

在高压配电所工程中，控制室的作用是（）。

A．接受电力

B．分配电力

C．预告信号

D．高压电转换成低压电
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填空题

World Health Organization (WHO) officials recently urged Asia-Pacific governments to shake off complacency and intensify the fight against tuberculosis (TB), which kills 1,000 people a day in the region. Shigeru Omi, regional director of WHO for the Western Pacific, said deaths caused by tuberculosis continue to rise in the region as ’more and more people are infected with the dreadful disease every year.
"Every year, an additional two million tuberculosis cases are diagnosed in the region," Omi said at a news conference during the opening of a two-day meeting of Asian’ parliamentarians to discuss strategies to control the disease. (41) "When it comes to developed countries, the reason for the increase of TB is related to the ageing society," he said." (42) ""One common fact among developing countries and developed countries is complacency, "Omi added." (43) "
WHO said among the "high burden, high risk" countries in the region are Cambodis, China, Laos, Mongolia, Papua New Guinea, the Philippines and Vietnam. (44) It noted that more that 40 million people are infected with the disease and "10 percent of them -will develop TB in their lifetime. "In Cambodia, more than 7 million people, or 60 percent of the population, are infected with the disease, while in Vietnam more than 145, 000 people are infected each year. "In several developed and newly industrialized countries in the Western Pacific region, TB prevalence has not decreased markedly during the last decade although economic growth should make more resources available to deal with the problem, "WHO said. (45) .
Omi expressed confidence that with renewed vigilance among health officials in the region. TB prevalence could be reduced by half by 2010.
[A] If you become elderly, your immune system is becoming weaker and weaker.
[B] In Japan, the number of diagnosed cases rose to 48, 264 in 1999 from 42, 472 cases in 1996.
[C] Omi pointed out that the main factor for the rise of TB cases in developing countries is the rapid increase of people who migrate into the big cities and live in unsanitary conditions.
[D] There is no doubt that tuberculosis will be eliminated completely everywhere in the world in the near future.
[E] They thought we have already conquered tuberculosis, so they become a little bit complacent.
[F] WHO records showed that in China, tuberculosis is one of the most common causes of death.
[G] In Asia, the number of diagnosed cases rose to 148, 264 in 2001 from 42, 472 cases in 2005.
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