搜题请搜索小程序“爱下问搜题”
问题 选择题

24mL浓度为0.05mol/L的Na2SO3溶液，恰好与20mL浓度为0.02mol/LK2R2O7溶液完全反应，则元素R在被还原的产物中的化合价是（    ）

A．+6

B．+3

C．+2

D．0

答案

答案：B

选择题

下列离子方程式书写正确的是（　　）

A．以石墨作电极电解CuCl2溶液：2Cl-+2H2O

 通电 
.
 
2OH-+Cl2↑十H2↑

B．FeSO4溶液与稀硫酸、双氧水混合：2Fe2++H2O2+2H+═2Fe3++2H2O

C．铜跟浓硝酸反应：Cu+4HNO3（浓）═Cu2++2NO3-+2NO↑+2H2O

D．NaHSO4溶液与足量Ba（OH）2溶液混合：2H++SO42-+Ba2++2OH-═BaSO4↓+2H2O
查看答案
听力题

根据句意和汉语注释，在空格内写出各单词的正确形式。

小题1:After watching such boring _______ (广告), she felt very bored and turned off the TV.

小题2:The sunny boy I know is _______ (幽默)in his class. 

小题3:The _______ (长途汽车)over there look very crowded. Shall we take a taxi instead?

小题4:The boy looked so _______ (紧张)at the teacher that he could say nothing.

小题5:The food cooked by his mother always _______ (尝)rather good, doesn't it?
查看答案