我国西南地区泥石流多发的主要自然原因是（    ）

①构造活跃     ②地形复杂     ③冬季多暴雨     ④破坏植被

Many Chinese brands, __________their reputations over centuries,are facing new challenges from the modern market.

 1967年，俄勒冈大学的径赛教练包尔曼和专门研究心脏的医学家哈里斯合著的《慢 跑》一书出版，大大促进了慢跑活动的普及．慢跑是一种中等强度的有氧运动．有氧运动衡量的标准是心率，心率保持在150次/分钟时的运动为有氧运动．请分析回答：

完形填空。

    Tom and his father are 1 in the playground. There is a cat and a dog there.  They are playing with a ball together. “I think the cat is 2 than the dog," Tom says, “I don't think so," his father says. “Why?"  “Because the dog looks 3 than the cat " Tom laughs and says, "But I like the cat.  It is white and it is 4 than the dog. " Tom's father says, “Dogs are my favourite animals because they are very 5 to me " "Yes, but I like smaller ones. Can we keep one?" Tom says. "of course," Tom's father says.