Oh,_______（天啊）!I saw a lion on the road just now.
下列有关分子与原子的说法不正确的是 A．温度越高分子的运动速度越快 B．在化学反应中分子可分，原子不可再分 C．气体受热后由
The salesgirls always gives customers _____ smile and the customers are very _____. A.pleasant; pleased B. pleased; pleased C. pleasant; pleasant D. pleased; pleasant
Last week we held a heating discussion on which we should do for our school before we graduate. The students in our class have different suggestion. Some students thought that we can collect money
2009年10月31日上午,享誉海内外的杰出科学家、我国航天事业的奠基人钱学森先生在北京逝世。钱学森用他的一生告诉我们，一个科学家，只有为国家和
如图所示的电路中，闭合开关S后，两个灯泡均不亮。为了诊断该电路的故障，现用一根导线接在AB两点之间，两个灯泡仍然均不亮；用导线接在BC两点之
用一种试剂就能把NaCl、NH4Cl、Na2SO4三种溶液区别开，这种试剂是A．AgNO3溶液B．NaOH溶液C．BaCl2溶液D．Ba(OH)2溶液
的方差为
，则数据
的标准差为 .