Choice Feature familiarizes us with the outside world and the living language.Usage Differentiation tells the minute variation of words of similar forms and avoids errors in daily communication.

• 它们的共同特征，就是以平和的语气，耐心而又善解人意地娓娓而谈，读者可能冷不防地发现，有些内容甚至可能直接用于工作和生活。