题目

下列关于细胞分化、衰老、凋亡和癌变的叙述，正确的（ ） ①个体发育过程中细胞的衰老对于生物体都是有害的②正常细胞癌变后在体外培养可无限增殖③由造血干细胞分化成红细胞的过程是可逆的④细胞癌变是细胞高度分化的结果⑤人胚胎发育过程中尾的消失是细胞亡的结果⑥原癌基因与抑癌基因不同，原癌基因调节细胞周期，阻止细胞不正常的增殖⑦低温引起的细胞冻伤和死亡属于细胞坏死 A . 1项 B . 2项 C . 3项 D . 4项Pressed from his parents, and ______ that he has washed too much time, the boy is determined to stop playing video games.A．realizing B．realized C．to realize D．being realized