简述轮胎滚动阻力的形成原因及影响因素？
参考答案：
弹性轮胎的迟滞损失。影响因素：行驶车速，轮胎的结构、帘线、橡胶的品种，轮胎的充气压力。
下列属于生产者与消费者之间关系的是（ ）
A．蛇吃青蛙
B．猫头鹰吃鼠
C．兔吃草
D．虎吃羊
Mrs Black eats _________ meat, so he is _________ fat now.[ ]
A. too much; much too
B. much too; too much
C. too much; too much
D. much too; much too
