【答案解析】[听力原文] 22-25
W: Dr Thomas? This is Keet Bradley from Daily News. I'd like to ask you some questions about the new official standard weight that you purchased.
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, 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.
W: How did you check the scales before?
M: We have an old standard weight that we used to use. It had to be replaced because it was imprecise. You see it was made of poor quality metal that was too porous. 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. Is it really worth that much?
M: I'm sure it is. 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.
本题要求概括对话的主旨。首先，对话是Daily News的记者电话采访Dr Thomas。其次，对话中出现了许多与尺度有关的关键词，如：weight，measure等，所以我们可以肯定他们谈论的是[B]项中的“衡量重量的标准单位”。
单选题
How was the weight used?
A. To check the accuracy of scales.
B. To calculate the density of other metals.
C. To observe changes in the atmosphere.
D. To measure amounts of rainfall.
【正确答案】
A
【答案解析】本题答案信息对应于第二轮对话中男士回答的第一句：the people in our department use it to check the scales all over the country(我们部门的人用它来检查全国的秤)。
单选题
Why was it necessary to replace the old standard weight?
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.
【正确答案】
C
【答案解析】第三轮对话中男士介绍了old standard weight，指出它是由poor quality metal(低质量的金属)制成，而在第四轮对话中谈到new standard weight时又用了higher quality一词。因此，将旧的标准砝码换成新的就是因为它是由poor quality metal制成，从而导致不精确，选[C]。
单选题
What does Dr Thomas probably think about the cost of the new weight?
A. It is a small amount to pay for so much precious metal.
B. It is difficult to judge the value of such an object.
C. It is reasonable for an object with such an important function.
D. It is too high for such a light weight.
【正确答案】
C
【答案解析】本题问Dr Thomas怎样看待new weight的成本。对话中Dr Thomas并没有直接表明自己的态度，但可以通过最后一轮对话中女士的问题和男士的回答推断出他认为it is worthwhile，故选[C]。