【单选题】听力原文: For many years, officials of the National Institutes of Health have told Americans that they need to get enough sleep to stay healthy and perform. well. In the past, the N-I-H targeted special g...
A.
To urge children to get enough sleep.
B.
To relieve the burden of school children.
C.
To dissuade teenagers from staying up late.
D.
To tell Americans to have 9 hours of sleep every night.