“凡是有生活的地方，就有快乐和宝藏。”这说明高雅的生活情趣（    ）    
①对生活的热爱                             ②只有历尽沧桑的人才能拥有的
③一定要有高雅的家庭环境        ④对生活积极的和美的感受 

下列二次根式中属于最简二次根式的是（　　）.

若分式$\frac{x+1}{x+2}÷\frac{x+3}{x+4}$有意义，求x的取值范围．

    铁路经过青龙桥附近，坡度特别大。火车怎么才能爬上这样的陡坡呢？詹天佑顺着山势，设计了一种“人”字形线路。

    Christmas is coming. Jenny and her family are very happy. They are getting ____ for the festival.

    Jenny is buying some Christmas ____ with her mother. Her father is cleaning the house. He ____ hard. Her grandmother is watching a TV programme about preparing (准备) special ____ What is her grandfather doing? Oh, he is decorating (装饰) a big Christmas ____.