A、Washington D. C. B、New York City. C、Chicago. D、Denver. A题目问的是去年夏天，女士在哪儿工作。由定位句可知，她去年夏天在华盛顿工作。故选A。

Last summer I was working in Washington, D. C. , as an intern at the Armed Forces Institute of Pathology. In one way it was an awful job because the purpose was to figure out ways to identify dead people, like identifying the remains of soldiers in wars, or bodies after disasters such as plane crashes or earthquakes. But the exciting part was that I was working with a scientist who heads a program that identifies bodies by their DNA structures. As you know, DNA is the name for the genetic material in our bodies. In the past, all soldiers had to wear a necklace and a metal tag with their names and identification numbers on the tag. But this method of identification was not very accurate because the tags could be lost or switched a-round.
    Q19: Where did the woman work the previous summer?
    Q20: What is the purpose of the program the woman is discussing?
    Q21: What did the speaker say was exciting about her work?