如果可能的话，选择感到困倦想睡觉的时间。
If possible, select a time to go to bed when you naturally begin to feel sleepy.
他精力是那样充沛，上他的课，你不会想睡觉（不会感到困倦）！
He's got so much energy, this is one class you do not fall asleep in!
他精力充沛，这是一节你不会想睡觉(感到困倦)的课。
He is full of energy, and you won't feel sleepy attending his class.
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