若，则事件与的关系是（ ） A. 互斥不对立 B. 对立不互斥 C. 互斥且对立 D. 以上答案均不
Most British telephone cards are just plain green, but card collecting is becoming a popular hobby in Britain and collectors even have their own magazine, International Telephone Cards. On
Who did the teacher ________ the exercises? A. have done B. have do C. had done D. has done
A friend of mine met with an accident driving in the darkness. His legs were so hurt that he couldn’t move. What was 1 , he found himself unable to ask for help—his mobile phone went out of
下列各项中不属于仿生的是（ ） A．萤火虫与冷光B．蝙蝠回声定位与雷达C．篮球与西瓜D．乌龟背甲与薄壳建筑
马克思曾说，在珍妮纺纱机发明之前，“要想找出一个能够同时纺出两根纱的纺织工人并不 比找出一个双头人容易”。中国能改变马克思这一断言
下列元素中，不属于同一周期的是 A．氢 B．硫 C．钠 D．氯
选用如下实验装置组合后完成用浓盐酸、二氧化锰共热制Cl2，并用Cl2和Ca(OH)2反应制少量漂白粉的实验。已知①工业制漂白粉反应为放热反应。②温度稍
的导数为
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B. 
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