面积居世界前三的国家依次是()、()、()。
素有“非洲屋脊”之称的山脉是()。
阿糖胞苷的作用机制
A.减少四氢叶酸生成而抑制蛋白质的合成
B.作用于核糖体而抑制蛋白质的合成
C.抑制DNA多聚酶
D.损害细胞膜而致细胞毒作用
E.与嘌呤或嘧啶竞争而抑制核酸合成
Why did Greg Woodburn gather worn shoes?
A.Because he believed running can bring good health, friendships and confidence.
B.Because he thought it was a waste of money to get rid of worn shoes.
C.Because he wanted to help the poor children who don"t even have shoes.
D.Because he hoped more children would like to help strangers like him.
金黄色葡萄球菌产生
A.内毒素
B.肠毒素
C.神经毒素
D.细胞毒素
E.红疹毒素
我国五大名山总称“五岳”,其中最高的是()。