复数形式是story books，例如：
When they reach six months, they will become interested in simple story books in rich colours.到了六个月,他们就会对色彩丰富的简单故事书感兴趣。
复数形式是story books，例如：
When they reach six months, they will become interested in simple story books in rich colours.到了六个月,他们就会对色彩丰富的简单故事书感兴趣。
