revolve
vi.旋转
The wheel began to revolve.轮子开始旋转。
reward
n.报答，奖赏;报酬 vt.报答，奖励
The school has a system of rewards and punishments to encourage good behaviour.学校有奖惩制度鼓励良好行为。
rhythm
n.节奏，韵律
Drums are basic to African rhythm.鼓是非洲音乐节拍的基础。
rigid
a.严格的，死板的;刚硬的，僵硬的
rigid and authoritarian methods of education死板、专断的教育方法
