【简答题】To us it seems that so natural to put up an umbrella to keep the water off the rains. But actually the umbrella was not invented as protection against rain. Its first use was as a shade against the su...
【简答题】写出下列反应的化学方程式,并完成题内填空. (1)写出加热碱式碳酸铜的化学方程式______.反应类型是______.生成物均属于______(选填“酸、碱、盐、氧化物”中一种). (2)将一枚生锈的铁钉(铁锈的主要成分是三氧化二铁),投入适量的稀硫酸中,溶液的颜色由无色变为______色,观察一段时间发现铁钉表面有气泡冒出,请写出上述反应的化学方程式______. (3)镁在空气中燃烧时,发出耀...
【简答题】完成下列反应的化学方程式并在括号内注明反应的基本类型. (1)工业制取二氧化碳______; (2)铁丝在氧气中燃烧______; (3)高温下碳还原氧化铜______; (4)氨气在加热条件下与氧化铜反应生成铜、水和空气中含量最多的气体.______.
【单选题】(变量作用域)有如下程序: #include int max(int x,int y) { int z; if(x>y) z=x; else z=y; return (z); } main() { extern int a,b; printf(“max=%d\n”,max(a,b)); } int a=3,b=5; 运行结果为( )
【简答题】One day the famous American scientist Albert Einstein(著名的美国科学家爱因斯坦) came across(碰到) an old friend of his in a street in New York. “Mr Einstein” said the friend “ It seems that you need to have a new o...
【简答题】Dear Peter, But first, I am sure that you are wrong that nobody will care if you leave your home. What about your parents? And other family members? It seems that you are very sad. You'd better go to ...