题目内容：
Questions 1 to 5 are based on the following passage:The first year of school in America, known as kindergarten, usually begins between the ages of five and six. Among rich countries such a late start is very' strange. President Obama believes it is an economic and social problem; his education secretary goes as far as to say that it is "morally wrong". This statement has some support, as it is clear from research into vocabulary that youngsters from poor families enter kindergarten well behind those from rich families-a disadvantage that usually lasts a lifetime. Children from households on welfare knew 525 words by the age of three, while the children of professionals had mastered 1,116.
(76) Pre-school can help close this gap. So in a speech last month, Mr. Obama called for a part- nership between the federal government and the states to expand it to every American child. It later became known that "every" meant those who come from families with incomes of up to 200% above the poverty line--equal to an income of $ 47,000 for a family of four.
(77) Some critics say that sending children to school at the age of four does not work. The evidence suggests otherwise. For example, on March 20th new results were announced from a study of 9 to 11-year-olds in New Jersey. This report found that disadvantaged children who had attended preschool had better literacy ( 读写能力 ), language, maths and science skills. And two years of pre-kin-dergarten were better than one.
Some studies also follow the effects of early learning over lifetimes, such as its effect on crime rates and other factors that may eventually burden society. Critics have singled out a government scheme called Head Start, created in 1965, which provides poor households with a range of services including school-based early education.
Kindergarten in rich countries other than America usually begins at the age of ________ A．Eight
B．seven
C．six.
D．Four
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