building blocks of life.

The algorithm is a step-by-step operation for solving problems. It is called "Geographic Population Structure, "or GPS. The report was prepared by researchers from the University of Sheffield in England, and the University of Southern California. It was published in the journal Nature Communications.

The researchers say GPS can find a village or tribe where genes became mixed as far back as 1, 000 years ago, during population movements or invasions. At such times, people from groups that were separated earlier came together and had children.

The British and American scientists tested their algorithm by studying genetic information from 200 individuals. The people were from 10 villages on the Italian island of Sardinia. GPS correctly placed 25 percent of the people directly in their villages. Most of the other individuals were placed within 50 kilometers of their villages. A test involving more than 20 islands in the Pacific Ocean produced similar results. In all, 98 percent of the information proved correct.

The scientists say the new method may be important not only for learning about ancestors, but also for health reasons. They say that knowing one's genetic code may show what conditions and sicknesses may be likely to affect a person.

But valuable as it may prove to be, there are more traditional ways that people can learn about their ancestry. Some families pass information about family history to the next generation. In turn, those children pass the information on to their children.

【语篇概述】本文主要介绍了新的计算程序GPS可以帮助人们找到自己的祖先。

1. Which of the following is TRUE?

A. GPS is an operation for inventions.

B. The result of the test is satisfactory.

C. All the 200 individuals found their ancestors.

D. GPS can cure patients of illnesses.

【解析】选B。细节理解题。根据第四段的实验可知新的计算程序GPS可以找到绝大多数参与者的祖先, 准确率甚至达到了98%。可知结果令人满意。

2. What can we learn from the last paragraph?

A. We don't need"Geographic Population Structure".

B. Other ways can also help us find our ancestors.

C. Traditional ways are better than"Geographic Population Structure".

D. We have already known about our ancestors.

【解析】选B。推理判断题。根据最后一段there are more traditional ways that people can learn about their ancestry可知除了"Geographic Population Structure", 许多传统方法也可以帮助人们找到自己的祖先。

3. What's the best title of the passage?

A. GPS is widely used in communication

B. GPS can help us with our health

C. GPS helps you find your ancestors

D. GPS has many shortcomings

【解析】选C。主旨大意题。本文主要介绍了新的计算程序GPS可以帮助人们找到自己的祖先。