A、Someone spilled water on it. B、Someone lost it. C、It was made of low quality metal. D、The standard for measuring had changed.

W: Dr. Thomas? This is Keet Bradley from the daily news. (9) I’d like to ask you some questions about the new official standard weight that you purchased.（女士说她想问男士几个关于新度量衡的问题，由此揭示对话谈论的主题是关于衡量重量标准的单位。）
M: I’d be happy to help you. What would you like to know?
W: First of all, how was the standard weight used?
M: Well, (10) the people in our department use it to check the scales all over the country. The department of weights and measures, we are a government agency. It’s our responsibility to see that all the scales measure a kilogram accurately so this is the way we use to adjust the scales.（男士说他们用新标准度量衡来检测全国的天平，他们有责任利用它来确保所有的天平都能够准确地测量1 公斤的重量）
W: How did you check the scales before?
M: We have an old standard weight that we used to use. (11) It had to be replaced because it was imprecise. You see it was made of poor quality metal that was too porous.（ 男士说旧天平会被取代是因为它不够精准，制造材料低劣。）It absorbed too much moisture.
W: Oh. So when the weather was humid it weighed more and when it was dry it weighed less.
M: Exactly. And that variation can affect the standards of the whole country. So our department had the new weight made out of higher quality metal.
W: How much did it cost?
M: About 45 thousand dollars.
W: 45,000 dollars? For one kilogram weight? That’s more expensive than gold. (12) Is it really worth that much?
M: (12) I’m sure it is.（女士问男士新度量衡是否物有所值，男士说确定如此。由此可以推断男士认为新度量衡是物有所值的。）Industries depend on our government agency to monitor the accuracy of scales so that when they buy and sell their products there is one standard. Think of the drug industry, for example, those companies rely on high accuracy scales to manufacture and package medicine.
Questions 9 to 12 are based on the conversation you have just heard.
9. What is the conversation mainly about?
10. What was the standard weight used to do?
11. Why was it necessary to replace the old standard weight?
12. What does Dr. Thomas probably think about the cost of the new weight?