狼体内有A种蛋白质，20种氨基酸；兔体内有B种蛋白质，20种氨基酸。狼捕食兔后狼体内的一个细胞中含有的蛋白质种类和氨基酸种类最可能是( ) A．A＋B
________ is known to us all is that the famous author, for ________ life was hard in the past, still works very hard in his eighties. A．What; whom B．As; whom C．It; whose D．What; whose
The UN passed a rule in the year 2004 to improve the quality of drink water and reduce deaths caused by drinking unhealthy water each year. The UN has already worked out the specific plan to reduce ha
下列有关酶的叙述不正确的是 A．酶需在最适温度下保存以保持最高活性 B．唾液淀粉酶的基本组成单位是氨基酸 C．同一种酶可以存在于不同的活细胞
图1表示某哺乳动物的一个器官中一些处于分裂状态的细胞图像，图2表示相关过程中细胞核内DNA含量变化曲线示意图，有关叙述中错误的是 A．图1中I
已知△ABC中，AB=；BC=6；CA=.点M是BC中点，过点B作AM延长线的垂线，垂足为D，则线段BD的长度是 .
山脉往往成为地形区的界线。华北平原和黄土高原之间的山脉是 A．大兴安岭 B．太行山 C．巫山 D．雪峰山
Yesterday，I came across my former classmate，but his name ________ me，which made me embarrassed. A．forgot B．missed C．escaped D．reminded
2H2O
＝