In most schools of the United States, students attend classes for 5 days each week. Schools are required to hold classes for about 180 days a year. Recently, schools in some areas of the country have begun experimenting with the new teaching arrangement of holding classes for 4 days a week. Classes would meet either Monday through Thursday, or Tuesday through Friday. Some schools in 12 American states are now using that schedule（日程安排）.
The students still have the same number of total hours in class as before. But they attend school for a longer time on each of the 4 days. In Colorado, schools on the four-day week hold classes for seven-and-one-half hours a day for 144 days. Traditional（传统的）schools meet for 6 hours a day for 180 days.
Many schools on a four-day schedule offer special programs, trips or sports meets on the fifth day. Officials say this gives students even more time in class than on the traditional schedule. Students do not have to miss school to go to the events. They can also go to doctors or deal with other important affairs on the fifth day.
The main reason for shortening the school week is that many small schools can save money by not providing meals or transportation for students on the fifth day. And they say research shows that students are not harmed by shorter week.
How long should the students spend in school in a day according to the new schedule?（ ）
由文章第二段可知，从前是6 hours a day，现在实行的新安排是seven-and-one-half hours，故选B。
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