根据短文内容,选择最恰当的答案
In the United States, most of the children
begin school at the age of three or four. When children are five, they begin
kindergarten and go to school for half a day. Between the ages of six and
twelve, students are in elementary school. Middle school or junior high school
students are thirteen and fourteen. Middle school is the level between
elementary and high school. Different middle schools have different numbers of
grade levels. The first middle school opened in 1960. Senior high school
students are between fifteen and eighteen. Many Chinese people think that
American students almost don't have any homework--it's wrong! Most senior high
school students in the USA have got as much homework as Chinese students do, and
they usually spend 2 to 3 boars doing their homework every day!