溶质质量分数分别为a%和5a%的H2SO4溶液等体积混合均匀后，则混合溶液中H2SO4的质量分数为 A．等于3a% B．等于6a% C．大于3a% D．小于3a%
通过下列化学反应不能达到目的的是( )A．制氯化铁：2Fe + 3CuCl2 = 2FeCl3 + 3Cu B．用稀硫酸除去炭粉中的少量氧化铜：CuO + H2SO4 = CuSO4 + H2O C．
阅读下面文段 ①从天而降的片片雪花给人们带来欢乐, 同时也给人们带来了无须额外投入的清洁能源。 ②专家推算, 10 万吨雪换算成等量
在如右图所示的电路中，当滑动变阻器的滑动头向上滑动时，A、B两灯亮度的变化情况为 （ ）A．A灯和B灯都变亮B．A灯和B灯都变暗C．A灯变亮，B
They often paly _______ on the badminton court.A．badmintonB．basketballC．footballD．volleyball
如图7，点D、E、F分别在AB、BC、AC上，且DE// AC, EF// AB ,下面写出了证明 “”的部分过程，请完成填空： DE// AC, EF // AB, ( ) .(
--Is there any possibility of the film ___________ in Paris International Festival? --Not in the least, because the audience generally think little of it. A. trying out B. tried out C. t
_______ how to do the homework, I went to ask my teacher for help. A. Not to know B. Not knowing C. Knowing not D. Not known
