Scientists are learning more about our【C1】______ for sleep. Most people sleep【C2】______ ei
To determine the【C15】______ of the lack of sleep, scientists have put subjects【C16】______ a set of psychological and performance tests【C17】______ them, for instance,【C18】______ columns of numbers or recall a passage read to them only minutes earlier, "We've found that if you're in sleep deficit (缺乏), performance suffers," says Dr. David. "Short-term memory is【C19】______ , as are abilities to【C20】______ decisions and to concentrate."
【C1】
A.request
B.need
C.want
D.fancy