单项选择题
A．television B．radio C．computer D．the writer
A．Getting off to work with a minimum effort helps save one’s energy. B．Dr. Kleitman explains why people reach their peak at different hours of day. C．Habit helps a person adapt to his own energy cycle. D．Children have energy cycles, too.
A．she learned to use scales B．she worked as an actress C．she went to work with her aunt D．she used toothpicks and candy to build a bridge