17．Weighing too much can be bad for your health，and being fat is a growing problem for both kids and adults around the world．In the U．S today，about 9million children over the age of 6are fat．
Sleep might be one answer to the problem of being fat．Past studies have shown a relation between sleeping less and weighing more，but scientists have had a hard time deciding"which came first，the chicken or the egg？"
To get a better idea of which cause which，scientists interviewed the parents of 785third grade students about how well their kids sleep that year．Three years later，the parents answered the same questions．
By sixth grade，18% of these kids were fat．The scientists found no relationship between weight and the students'race or sex．It also didn't matter how strict their parents were，or whether they were boys or girls．Being fat is a problem of these group equally．
Instead，sleep seemed to be the main reason．For the six grade students，every night of sleep above the 9.5-hour average caused a 20% lower risk of being fat．Sleep appeared more important for the third grade students．One more hour of sleep they get led to 40% less in fatness before third grade．
66．What is main idea of the passageC？
A．Being fat is a growing problem B．Scientists had a hard time in interviewing
C．Sleeping less causes weighing more
67．How many parents are interviewedA？
A．Just 785 B．a(chǎn)bout 150 C．a(chǎn)bout 9million
68．What is the reason for being fatC？
A．race or sex B．parents C．sleeping time．
69．Which is true about the six grade students according to the passageC？
A．Less than 40% of the six grade students became fat．
B.18% of the six grade students got fat．
C.20% of the six grade students slept over 9.5hours a night．
70．What is the suggestion for the third grade studentsA？
A．They should sleep for about 9.5hours every night．
B．One more hour of sleep a night can make them fat．
C．Eating chicken and egg is good for them．
