题目内容
WASHINGTON(AP)——Human beings may have had a brush with extinction 70,000 years ago,all extensive genetic(基因的)study suggests.
The human population at that time was reduced to small separate groups in Africa,apparently because of dry climate,according to an analysis.A study by researchers at Stanford University pointed out that the number of early humans may have decreased as low as 2.000 before numbers began to expand again in the early Stone Age.
“This study shows the extraordinary power of genetics to expose some of the key events in our history。”Spencer Wells,National Geographic Society explorer。said in a statement.“Tiny groups of early humans,forced apart by severe environmental conditions,came back to reunite and populate the world,which was written in our DNA.”
Previous studies using mitochondrial DNA—which is passed down through mothers—have found the origins of modern humans related to a single“mitochondrial Eve,”who lived in Africa about 200,000 years ago.It seems that humans began to move out of Africa to populate the rest of the world about 60,000 years ago.
The researchers concluded that humans separated into small populations before the Stone Age,when they came back together and began to increase in numbers and spread to other areas.Eastern Africa experienced a series of severe dry weather between l35,000 and 90,000 years ago and the researchers said this climatological shift may have contributed to the population changes,dividing into small,separate groups which developed independently.As recently as 70,000 years ago,extremes of climate had reduced our population to such small numbers that we were on the very edge of extinction.
1.Scientists found that humans were likely to be extinct by studying .
A.climate changes B.people’s DNA C.human’s history D.old environment
2.The scientists did the research in Africa because .
A.humans began to come and live in the rest of the world 70.000 years ago
B.DNA in the people of Africa can be passed down through mothers
C.only humans in Africa faced severe environmental conditions
D.human beings are considered to have originated from Africa
3.The period when humans kept in small populations probably last .
A.60.000 years B.10,000 years C.20,000 years D.45,000 years
4.What can we learn from the last pagraph?
A.It seldom rained for a long time,which decreased our population.
B.People lived together to fight against the climate changes.
C.People were divided into small groups to hunt more animals.
D.People returned in the Stone Age and the number increased.
5.Which of the following is the best title of the passage?
A.Humans may have extinction 70,000 years ago
B.Stone Age:A period when our population increased
C.Getting out of our homeland-Africa
D.Severe droughts will cause extinction of humans
BDBAA
Shirley Allen loved to sing and play the piano. She studied music in college and her 36 was to become a concert pianist or blues singer.
Everything 37 when she was 20 years old. She became sick with what doctors 38 was typhoid fever(伤寒)and she almost died. Doctors gave her medicine to help her get well, but the medicine 39 her to become 40 deaf. She could no longer hear the music which she had always 41.
Shirley would never give up playing the piano, 42 she did decide to change 43 . She transferred to Gallaudet University and studied English. In 1964 Shirley graduated from Gallaudet and looked for 44 . She wanted to be 45 and work full-time.
For three years, Shirley worked as a clerk in Washington, D.C. 46 , in 1967 she was asked to work at Gallaudet University as a dorm supervisor (宿舍监管员). Shirley supervised young women who 47 in the university during the school year. She also taught English. Somehow she found time to 48 graduate school at Howard University in Washington, D.C. In 1972, Shirley received her M.A. degree.
Always 49 a new challenge, in 1973 Shirley became a professor at National Technical Institute for the Deaf (NTID),which 50 deaf and hard-of-hearing students technical and professional training.
This 51 woman became the first black deaf female in the world to receive her Ph.D. She made 52 in 1992, 53 she received the highest degree in education from the University of Rochester in New York.
Dr. Shirley Jeanne Allen has traveled many roads and 54 many rainbows searching for her dream. With courage and 55, she never gave up.
1. |
|
2. |
|
3. |
|
4. |
|
5. |
|
6. |
|
7. |
|
8. |
|
9. |
|
10. |
|
11. |
|
12. |
|
13. |
|
14. |
|
15. |
|
16. |
|
17. |
|
18. |
|
19. |
|
20. |
|
Events Calendar
TUESDAY
Landscape Pests (害虫)
Learn to identify, control and prevent seasonal landscape-disease and landscape-pest problems at the workshop, 3:30 pm. – 5 pm. Tuesday at the US National Arboretum, 3501 New York Ave NE, Washington. $15; registration required.
202-245-4521 or www.usna.usda.gov.
THROUGH AUGUST 3
Horticultural(园艺的) Art
Watercolors, pen-and-ink drawings and colored-pencil pieces by the Brookside Gardens School of Botanical (植物学的) Art and Illustration will be on display at the exhibit Botanic 2007: The Art and Science of Plants at Brookside Gardens Visitors Center, 1800 Glenallan Ave, Wheaton, through Aug. 3. Free. 301-962-1400 or www.brooksidegardens.org.
THROUGH SEPTEMBER 9
Botanical Art
Visit Patterns in Nature, an exhibit by Amy Lamb featuring photographs of flowers, leaves and other botanical life, at the US Botanic Garden Conservatory (温室),West Orangerie, 100 Maryland Ave SW, Washington, through Sept. 9. The conservatory is open 10 am. – 5 pm. Daily. Free. 202-225-8333.
THROUGH OCTOBER 8
Botanic Garden Exhibit
Celebrating America’s Public Gardens is on view through Oct. 8 at the US Botanic Garden, 100 Maryland Ave SW, Washington. The exhibit, on the Conservatory Terrace and in the National Garden, features displays of 20 public botanic gardens across the country. Hours are 10 am. – 5 pm. Daily. Free. 202-200-8956.
1.If you want to record your name for an event in advance, you may call _____.
A.202-225-8333 |
B.202-245-4521 |
C.301-962-1400 |
D.202-200-8956 |
2. If you go to Botanic Garden Exhibit, you _____.
A.can enjoy drawings and coloured-pencil pieces |
B.can learn how to kill pests living on the plants |
C.can find displays of 20 botanic gardens across the country |
D.will enjoy the photographs of flowers and leaves |
3. From the advertisement, we learn _____.
A.the first event is about growing healthy plants |
B.all of the events are free of charge |
C.there is no time limit to all the events |
D.you can find the information of all the events either by phone or by e-mail |