A studysurveying more than 2500 American high school students found __小题1:__ girls who ate five or more family meals a week had a much healthier relationship with food in __小题2:__ (late) life．
The research, __小题3:___ (publish) in international magazine Archives of Pediatrics and Adolescent Medicine, polled students aged 13 to 17 in 1999 ___小题4:__ were followed up five years later．Regular family meals were found to have a protective effect regardless of the girls’ age , weight, socio-economic status, dieting habits or relationship with her family．
Experts say doctors should encourage families ___小题5:__ (have) dinner at the table rather than on the couch in front of the television to keep away from serious eating disorders．
Belinda Dalton, director of eating disorders clinic the Oak House, said __小题6:__ (eat) with family helped "normalize" young people's relationship with food．
"When the young are feeling that they're not dealing properly, they turn to __小题7:___ that they can control and food is accessible for them to control. Clearly, if they're sitting with their family __小题8:___ a regular basis then their family can be more in control of their eating,"
，式中x、t分别以cm、s为单位，则位置x=4cm处的质元在t=1s时刻的振动速度v为（）。