One of the most important social developments that helped to make possible a shift in thinking about the r01e of public education was the effect of the baby boom of the 1950s and 1960s on the schools. In the 1920s, but especially in the Depression conditions of the 1930s, the United States experienced a declining birth rate—every thousand women aged fifteen to forty-four gave birth to about 118 live children in 1920, 89.2 in 1930, 75.8 in 1936, and 80 in 1940. With the growing prosperity brought on by the Second World War and the economic boom that followed it, young people married and established households earlier and began to raise larger families than had their predecessors during the Depression. Birth rates rose to 102 per thousand in 1946, 106.2 in 1950, and 118 in 1955. Although economics was probably the most important determinant, it is not the only explanation for the baby boom. The increased value placed on the idea of the family also helps to explain this rise in birth rates.
The baby boomers began streaming into the first grade by the mid-1940s and became a flood by 1950. The public school system suddenly found itself overtaxed. While the number of schoolchildren rose because of wartime and postwar conditions, these same conditions made the schools even less prepared to cope with the flood. The wartime economy meant that few new schools were built between 1940 and 1945. Moreover, during the war and in the boom times that followed, large numbers of teachers left their profession for better-paying jobs elsewhere in the economy.
Therefore, in the 1950s and 1960s, the baby boom hit an antiquated and inadequate school system. Consequently, the "custodial rhetoric" of the 1930s and early 1940s no longer made sense; that is, keeping youths aged sixteen and older out of the labor market by keeping them in school could no longer be a high priority for an institution unable to find space and staff to teach younger children aged five to sixteen.
With the baby boom, the focus of educators and of laymen interested in education inevitably turned toward the lower grades and back to basic academic skills and discipline. The system no longer had much interest in offering nontraditional, new, and extra services to older youth.
According to the passage, what is the main factor contributed to the baby boom

A:Economy. B:Public education. C:Family. D:Earlier marriage.

One of the most important social developments that helped to make possible a shift in thinking about the r01e of public education was the effect of the baby boom of the 1950s and 1960s on the schools. In the 1920s, but especially in the Depression conditions of the 1930s, the United States experienced a declining birth rate—every thousand women aged fifteen to forty-four gave birth to about 118 live children in 1920, 89.2 in 1930, 75.8 in 1936, and 80 in 1940. With the growing prosperity brought on by the Second World War and the economic boom that followed it, young people married and established households earlier and began to raise larger families than had their predecessors during the Depression. Birth rates rose to 102 per thousand in 1946, 106.2 in 1950, and 118 in 1955. Although economics was probably the most important determinant, it is not the only explanation for the baby boom. The increased value placed on the idea of the family also helps to explain this rise in birth rates.
The baby boomers began streaming into the first grade by the mid-1940s and became a flood by 1950. The public school system suddenly found itself overtaxed. While the number of schoolchildren rose because of wartime and postwar conditions, these same conditions made the schools even less prepared to cope with the flood. The wartime economy meant that few new schools were built between 1940 and 1945. Moreover, during the war and in the boom times that followed, large numbers of teachers left their profession for better-paying jobs elsewhere in the economy.
Therefore, in the 1950s and 1960s, the baby boom hit an antiquated and inadequate school system. Consequently, the "custodial rhetoric" of the 1930s and early 1940s no longer made sense; that is, keeping youths aged sixteen and older out of the labor market by keeping them in school could no longer be a high priority for an institution unable to find space and staff to teach younger children aged five to sixteen.
With the baby boom, the focus of educators and of laymen interested in education inevitably turned toward the lower grades and back to basic academic skills and discipline. The system no longer had much interest in offering nontraditional, new, and extra services to older youth.

According to the passage, what is the main factor contributed to the baby boom（）

A:Economy B:Public education C:Family D:Earlier marriage

England is not a big country: from north to south and from east to west it is only about three hundred miles across. But for a small country it has a surprising range of climate. People who have never visited England or who have visited only one part of it often makes the mistake of thinking that it is a cold and wet country. Except for the summer months of June to September, this is probably true of the north of England and the Midlands. In the south, however, the climate is much more pleasant. One result is that when people retire from the job in the north, they often prefer to move down to the south.
Perhaps the warmest part of the country is the southwest, which consists of(is made up of) the counties of Devon and Cornwall, where palm trees, bamboo and many semitropical plants grow well. Flowers and vegetables ripen as much as a month earlier than those elsewhere. Farmers in the areas gain a higher price for their vegetables and flowers because they are ready earlier. In winter there may be several feet of snow in other parts of England but there will probably be no snow at all in the southwest. This may be one of the reasons why the southwest is one of England’s most popular holiday areas.

According to the passage, （　）

A:flowers and vegetables from Devon are on the market one month earlier B:farmers in the southwest grow as many vegetables and flowers as farmers elsewhere C:people in the southwest have to pay a higher price for vegetables and flowers D:vegetables in Cornwall ripen as much as a month earlier than flowers

England is not a big country: from north to south and from east to west it is only about three hundred miles across. But for a small country it has a surprising range of climate. People who have never visited England or who have visited only one part of it often makes the mistake of thinking that it is a cold and wet country. Except for the summer months of June to September, this is probably true of the north of England and the Midlands. In the south, however, the climate is much more pleasant. One result is that when people retire from the job in the north, they often prefer to move down to the south.
Perhaps the warmest part of the country is the southwest, which consists of (is made up of) the counties of Devon and Cornwall, where palm trees, bamboo and many semitropical plants grow well. Flowers and vegetables ripen as much as a month earlier than those elsewhere. Farmers in the areas gain a higher price for their vegetables and flowers because they are ready earlier. In winter there may be several feet of snow in other parts of England but there will probably be no snow at all in the southwest. This may be one of the reasons why the southwest is one of England’s most popular holiday areas.

According to the passage, （）

A:flowers and vegetables from Devon are on the market one month earlier B:farmers in the southwest grow as many vegetables and flowers as farmers elsewhere C:people in the southwest have to pay a higher price for vegetables and flowers D:vegetables in Cornwall ripen as much as a month earlier than flowers

England is not a big country: from north to south and from east to west it is only about three hundred miles across. But for a small country it has a surprising range of climate. People who have never visited England or who have visited only one part of it often makes the mistake of thinking that it is a cold and wet country. Except for the summer months of June to September, this is probably true of the north of England and the Midlands. In the south, however, the climate is much more pleasant. One result is that when people retire from the job in the north, they often prefer to move down to the south.
Perhaps the warmest part of the country is the southwest, which consists of(is made up of) the counties of Devon and Cornwall, where palm trees, bamboo and many semitropical plants grow well. Flowers and vegetables ripen as much as a month earlier than those elsewhere. Farmers in the areas gain a higher price for their vegetables and flowers because they are ready earlier. In winter there may be several feet of snow in other parts of England but there will probably be no snow at all in the southwest. This may be one of the reasons why the southwest is one of England’s most popular holiday areas.
According to the passage, ______.

A:flowers and vegetables from Devon are on the market one month earlier B:farmers in the southwest grow as many vegetables and flowers as farmers elsewhere C:people in the southwest have to pay a higher price for vegetables and flowers D:vegetables in Cornwall ripen as much as a month earlier than flowers

Passage Three
England is not a big country: from north to south and from east to west it is only about three hundred miles across. But for a small country it has a surprising range of climate. People who have never visited England or who have visited only one part of it often makes the mistake of thinking that it is a cold and wet country. Except for the summer months of June to September, this is probably true of the north of England and the Midlands. In the south, however, the climate is much more pleasant. One result is that when people retire from the job in the north, they often prefer to move down to the south.
Perhaps the warmest part of the country is the southwest, which consists of (is made up of) the counties of Devon and Cornwall, where palm trees, bamboo and many semitropical plants grow well. Flowers and vegetables ripen as much as a month earlier than those elsewhere. Farmers in the areas gain a higher price for their vegetables and flowers because they are ready earlier. In winter there may be several feet of snow in other parts of England but there will probably be no snow at all in the southwest. This may be one of the reasons why the southwest is one of England’s most popular holiday areas.

According to the passage（）

A:flowers and vegetables from Devon are on the market one month earlier B:farmers in the southwest grow as many vegetables and flowers as farmers elsewhere C:people in the southwest have to pay a higher price for vegetables and flowers D:vegetables in Cornwall ripen as much as a month earlier than flowers

England is not a big country: from north to south and from east to west it is only about three hundred miles across. But for a small country it has a surprising range of climate. People who have never visited England or who have visited only one part of it often makes the mistake of thinking that it is a cold and wet country. Except for the summer months of June to September, this is probably true of the north of England and the Midlands. In the south, however, the climate is much more pleasant. One result is that when people retire from the job in the north, they often prefer to move down to the south.
Perhaps the warmest part of the country is the southwest, which consists of (is made up of) the counties of Devon and Cornwall, where palm trees, bamboo and many semitropical plants grow well. Flowers and vegetables ripen as much as a month earlier than those elsewhere. Farmers in the areas gain a higher price for their vegetables and flowers because they are ready earlier. In winter there may be several feet of snow in other parts of England but there will probably be no snow at all in the southwest. This may be one of the reasons why the southwest is one of England’s most popular holiday areas.
According to the passage, ______.

A:flowers and vegetables from Devon are on the market one month earlier B:farmers in the southwest grow as many vegetables and flowers as farmers elsewhere C:people in the southwest have to pay a higher price for vegetables and flowers D:vegetables in Cornwall ripen as much as a month earlier than flowers

The vaccine -a combination of two earlier experimental vaccines -was given to 16,000 people in Thailand. Researchers found that it reduced by nearly a third the risk of contracting HIV, the virus that lcads to Aids.
It has been hailed as a significant, scientific: breakthrough, but a global vaccine is still some way off. The study was carried out by the US army and the Thai government over seven years on volunteers - all HIV - negative men and women aged between 18 and 30 - in parts of Thailand.
Half of the volunteers were given the vaccine, while the other half were given a placebo - and all were given counselling on HIV/Aids prevention. Participants were tested for HIV infection every six months for three years. The results found that the chances of catching HIV were 31.2% less for those who had taken the vaccine - with 74 people who did not get the vaccine infected and 51 of the vaccinated group infected.
The vaccine is based on B and E strains of HIV that most commonly circulate in Thailand not the C strain which predominates in Africa. "This result is tantalisingly encouraging. The numbers are small and the difference may have been due to chance, but this finding is the first positive news in the Aids vaccine field for a decade," said Dr Richard Horton, editor of the Lancet medical joumal.
"We should be cautious, but hopeful. The discovery needs urgent replication and investigation. "
Dr Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases said: "For the first time, an investigational HIV vaccine has demonstrated some ability to prevent HIV infection amorig vaccinated individuals. "
"Additional research is needed to better understand how this vaccine regimen reduced the risk of HIV infection, but this is certainly an encouraging advance for the HIV vaccine field. "
The findings were hailed by the World Health Organization (WHO)and the Joint United Nations Programme on HIV/Aids (UN/Aids). They said while the results were" characterised as modestly protective... [they] have instilled new hope in the HIV vaccine research field".
What is the new vaccine composed of

A:Two earlier experimental vaccines. B:Tens of older vaccines. C:Placebo. D:Not mentione