下图漫画说明生命科学面临的难题是( )
A:器官移植是否合理
B:人伦关系的混乱
C:人为地改变物种的遗传基因,会不会破坏现有的生态平衡
D:创造出的新物种,会不会导致原有的物种退化
两相邻匀强磁场区域的磁感应强度大小不同、方向平行.一速度方向与磁感应强度方向垂直的带电粒子(不计重力),从较弱磁场区域进入到较强磁场区域后,粒子的( )
下列哪项叙述完全符合生态经济( )
①建立“原料﹣产品﹣原料﹣产品”的无废料生产体系;
②在资源不增加甚至减少的条件下实现经济增长;
③在经济产出不变甚至增加的条件下,向环境排放的废弃物大大减少;
④先生产后治理,提高经济效益.
____This is a picture of my uncle's family. These are my uncle and aunt. Those are their children(孩子),Li Ming and Li Ling.
____ Look at the picture. This is my friend. His name is Jack.
____Here's a photo of my family. These are my grandparents. Those are my parents. This is me.
____Look at this picture. This is my father and that is my mother.
____ Look at the three boys. They are my cousins and me.
A B C
D E
在下列分类等级中,最大的分类等级是( )