A.20% of all high school students fall asleepin school during school time
B.Most students go to bed at 9：00 p.m.and wake up at 6：00A.m.to get a good nine hours of sleep before 11：00 in the evening
C.People are likely to fall asleep before 11：00 in the evening
D.Most high school students need at least 9 hours of sleep a day