要求:①将题目空缺处补充文章。②除诗歌外体裁不限,不少于600字。③文中不得出现(或暗示)真实的人名、校名、地名。
a.下列用品中,主要利用金属导电性的是(填字母)
A.铂金饰品 B.铁锅 C.铝导线
b.为了验证铝、铜、银三种金属的活动性顺序,设计了下列四种方案,其中可行的是(填序号)
①将铝、银分别浸入到硫酸铜溶液中
②将银分别浸入到硫酸铝、硫酸铜溶液中
③将铜、银分别浸入到硫酸铝溶液中
④将铜分别浸入到硫酸铝、硝酸银溶液中
c.在氯化铜和氯化亚铁的混合溶液中加入一定质量的镁粉,充分反应后过滤,得到滤渣和滤液.①滤液中一定含有的溶质是(填化学式);②向滤渣中滴加稀盐酸,有气泡产生,则滤渣中一定含有的物质是(填化学式).
是两条直线,
是两个平面,则
的一个充分条件是( )
B .
C .
D .
据此完成下面小题。
中,侧棱
底面
,
,且点M和N分别为
和
的中点.
的正弦值;
为棱
上的点,若直线
和平面
所成角的正弦值为
,求线段
的长
稳定旋转时,下列表述正确的是( )

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