睡眠时相推迟综合征(delayedsleepphasesyndrome)
参考答案:
由于青春期神经内分泌分泌模式变化引起睡眠时间的推迟,表现为入睡困难和早晨难以觉醒。
Tim's mum is worried _____ her son's eyesight as he plays online games too much. [ ]
A. for
B. about
C. with
D. of
标志中国半殖民地半封建社会完全形成的历史事件是()。