Do you know how much your children sleep? According to the National Sleep Foundation, should sleep twelve to eighteen hours of every twenty-four. With a gradual to twelve to fourteen hours for toddlers(初学走路的孩子) one to three; eleven to thirteen hours for three to five; and ten to eleven hours for schoolchildren five to ten. But things get really at adolescence. Not only do teenagers need more sleep than __---eight and a half to nine and a quarter hours a night, according to the sleep foundation - but the times which they get sleepy and are able to awaken and feel rested shift in a that does not match to the times at most schools. Sleep studies have shown that the typical teenager does not fall asleep readily before 11 p. m. or later. many have to get up by 6 a. m. or to get to school for a class starts at 7:30 or 8 a.m. More than a few off during that class, and often the one as well. Even if awake, they're in no condition to learn much of anything. In one study, more than 90 percent of teenagers they slept less than the nine hours a night, and 10 percent said they slept less than six hours. _ James B. Maas, a Cornell University psychologist and Leading sleep researcher, has observed, most teenagers are 'walking zombies(僵尸)' they get far too little sleep. 小题1: A．children B．newborns C．elders D．youngsters 小题2: A．from B．with C．out D．up 小题3: A．reduction B．increase C．growth D．improvement 小题4: A．teenagers B．students C．babies D．preschoolers 小题5: A．related B．separated C．aged D．varied 小题6: A．demanding B．challenging C．satisfying D．encouraging 小题7: A．adults B．toddlers C．babies D．schoolchildren 小题8: A．in B．on C．at D．for 小题9: A．excitedly B．early C．casually D．naturally 小题10: A．form B．means C．method D．way 小题11: A．end B．start C．holiday D．examination 小题12: A．Since B．For C．Yet D．Then 小题13: A．nicer B．earlier C．cleaner D．better 小题14: A．that B．its C．what D．whose 小题15: A．put B．take C．doze D．cut 小题16: A．next B．other C．last D．new 小题17: A．examined B．surveyed C．reported D．convinced 小题18: A．regulated B．recommended C．analyzed D．reported 小题19: A．Like B．Since C．As D．Furthermore 小题20: A．because B．which C．while D．still