Since the beginning of human evolution, men have migrated（迁移）across continents in search of food, shelter, safety, and comfortable weather. People still move for these reasons, but new reasons for human migration are arising, such as job relocation(重新安置) and overpopulation.
    Three million migrants are moving from poor countries to wealthier ones each year, and increasingly, their destination is a neighboring country in developing parts of the world. People are moving within the developing world for the same reasons as they migrate to wealthier nations. People from poor countries are going to less poor countries, fleeing wars and conflicts. They are also responding to population pressures because some countries are densely populated, and they often have high population growth. Those people need to go somewhere else.
    There are three main reasons why people move. The basic categories and percentages are as follows, according to the Current Population Surveys (CPS):
    Family-related reasons account for 26.3%, including changes in marital（婚姻的） status, establishing a household and other family reasons; work-related reasons 16.2%, including job transfer, retirement, and other job-related reasons; housing-related reasons 51.6%, including new and better houses, better neighborhood, cheaper housing and other housing reasons; the remaining 5.9% of other reasons are attending college, the change of climate and health reasons.
    Americans have been migrating south and west for decades in search of better job opportunities and warmer climates. They have also been moving to places a little far from cities, in search of bigger yards and houses, lower crime rates and better schools. In 1950, nearly a fifth of the population lived in the nation’s 20 largest cities. In 2006, it was about one in ten. That’s why many American people say, “Big Cities Shrink as People Move South, West.”
    Between March 2005 and March 2007, 73.4 million Americans moved. Fifty-six percent of these moves were within the same country. Twenty percent were between counties but in the same state. Nineteen percent were moves to a different state. Some families even went abroad.
Title: People on the   71 

根据对话内容，从对话选项中选出能填入空白处的最佳选项．选项中有两项为多余选项

—Good morning, International Student Office．　1　

—I'd like to talk to the coordinator(协调员) about my transfer(转学) to another university．

— 　2　

—No． I'm from the People's Republic of China．　　 I came last September．

—I see． Jim Kennelly can see you next Wednesday．　3　

—Morning is best for me．

—Would 9∶30 be all right?

— 　4　　　

— Good. We'll expect you then at 9:30 on Wednesday morning.

— 　5　　　

A．Do you come this afternoon?

B．Thank you very much．

C．Man I help you?

D．Are you one of the students from Singapore?

E．Yes, I am．

F．That suits me fine．

G．Do you prefer morning or afternoon?

　　With only about 1,000 pandas left in the world, China is desperately trying to clone(克隆) the animal and save the endangered species(物种). That's a move similar to what a Texas A．& M University researchers have been undertaking for the past five years in a project called “Noah's Ark”.

　　Noah's Ark is aimed at collecting eggs, embryos(胚胎), semen and DNA．of endangered animals and storing them in liquid nitrogen. If certain species should become extinct, Dr. Duane Kraemer, a professor in Texas A．&. M's College of Veterinary Medicine, says there would be enough of the basic building blocks to reintroduce the species in the future.

　　It is estimated that as many as 2,000 species of mammals, birds and reptiles will become extinct in over 100 years. The panda, native only to China, is in danger of becoming extinct in the next 25 years.

　　This week, Chinese scientists said they grew an embryo by introducing cells from a dead female panda into the egg cells of a Japanese white rabbit. They are now trying to implant the embryo into a host animal.

　　The entire procedure could take from three to five years to complete.

　　“The nuclear transfer(核子移植) of one species to another is not easy, and the lack of available(capable of being used) panda eggs could be a major problem.” Kraemer believes. “They will probably have to do several hundred transfers to result in one pregnancy(having a baby). It takes a long time and it's difficult, but this could be groundbreaking science if it works. They are certainly not putting any live pandas at risk, so it is worth the effort,” adds Kraemer, who is one of the leaders of the Project at Texas A．& M, the first－ever attempt at cloning a dog.

　　“They are trying to do something that's never been done, and this is very similar to our work in Noah's Ark. We're both trying to save animals that face extinction. I certainly appreciate their effort and there's a lot we can learn from what they are attempting to do. It's a research that is very much needed.”

1．The aim of “Noah's Ark” project is to ________.

[　　]

A．make efforts to clone the endangered pandas

B．save endangered animals from dying out

C．collect DNA．of endangered animals to study

D．transfer the nuclear of one animal to another

2．According to Professor Kraemer, the major problem in cloning pandas would be the lack of ________.

[　　]

A．available panda eggs

B．host animals

C．qualified researchers

D．enough money

3．The best title for the passage may be ________.

[　　]

A．China's Success in Pandas Cloning

B．The First Cloned Panda in the World

C．Exploring the Possibility to Clone Pandas

D．China－the Native Place of Pandas Forever

4．From the passage we know that ________.

[　　]

A．Kraemer and his team have succeeded in cloning a dog

B．scientists try to implant a panda's egg into a rabbit

C．Kraemer will work with Chinese scientists in clone researches

D．about two thousand of species will probably die out in a century