简要分析1857—1859年印度民族大起义的历史意义。

下列条件中，容易形成降水的是（ ）
①从低纬度流向高纬度的气流  ②从高纬度流向低纬度的气流
③从高空中下沉到地面的气流  ④从地面上升到高空中的气流．

若用两种识别切割序列完全不同的限制酶E和F从基因组DNA上切下目的基因（1.2kb，1kb=1000对碱基），并将之取代质粒pZHZ1(3.7kb)上相应的E—F区域 (0.2kb)，那么所形成的重组质粒pZHZ2 

     Joan is an American girl. She lives in China now. She is in my class. Her parents work in China, too, but her brother works in the U.S.A. He often writes letters to them. Joan likes Chinese class very much, and likes speaking Chinese with us after class. Her father teaches us English well. We all like his class. On Sundays, Joan goes to the People's Park with her father and mother. Sometimes she goes shopping with her mother. They like the Chinese food very much. It's a happy family.

七年级同学在排演历史剧《汉武帝》，其中有一场景是汉武帝与朝臣议事。请你指出下列场景设计中有历史知识错误的一项（   ）。