It was Japan ______launched the war against China.

A．Unawareness of energy cycles.
B．A change in a family member’s energy cycle.
C．Familiar saying.
D．Attempts to control the energy of other family members.

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 one adapt to his own energy cycle.
D．Children have energy cycles, too.