单项选择题
A．change his energy cycle B．get up earlier than usual C．overcome his laziness D．go to bed earlier
A．Getting off to work with a minimum effort helps save one's energy. B．Dr. Kleitman explains why people reach their peaks at different hours of day. C．Habit helps a person adapt to his own energy cycle. D．Children have energy cycles, too.
A．help to keep your energy for the day's work B．help you to control your temper early in the day C．enable you to concentrate on your routine work D．keep your energy cycle under control all day