A:对有基因缺陷的细胞提供营养,从而使其恢复正常,达到治疗疾病的目的
B:把健康的外源基因导入到有基因缺陷的细胞中,达到治疗疾病的目的
C:运用人工诱变的方法,使有基因缺陷的细胞发生基因突变恢复正常
D:运用基因工程技术,把有缺陷的基因切除,达到治疗疾病的目的
作文:
以“不寻常的考试”为题,写一篇不少于600字的文章。
Tom几岁了?
多多和爸爸、妈妈周末到动物园游玩,回到家后,她利用平面直角坐标系画出了动物园的景区地图,如图所示.可是她忘记了在图中标出原点和x轴、y轴.只知道马场的坐标为(﹣3,﹣3),你能帮她建立平面直角坐标系并求出其他各景点的坐标?
I think that the world will be an easy place to live in. We1have machines and robots and they will2us do all the3jobs, and we don't have to do things4washing dishes and5the beds, though we won't have any dishes at all. Maybe we will just throw the dishes away after each meal. I6that doctors will be able to7us alive8a long time. I hope that when I am 80 years old, there9something that can keep me alive for1080 years, so I will live to be 160 years old.