能正确表示下列反应的离子方程式是（） A．向KHSO4溶液中加入_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题选择题

能正确表示下列反应的离子方程式是（）

A．向KHSO₄溶液中加入Ba(OH)₂溶液至恰好沉淀完全

Ba²⁺+OH^－+H⁺+SO₄²^－=BaSO₄↓+H₂O

B．铁跟稀硫酸反应：2Fe + 6H⁺═ 2Fe³⁺ + 3H₂↑

C．碳酸钙与醋酸反应：CaCO₃+2H⁺═ Ca²⁺ + CO₂↑ + H₂O

D．硫酸铜溶液跟氢氧化钡溶液反应：Ba²^＋＋SO₄²^－＝BaSO₄

答案

答案：A

题目分析：B不正确，铁和稀硫酸反应生成硫酸亚铁和氢气；C不正确，醋酸是弱酸，应该用化学式表示；D不正确，反应中还有氢氧化铜蓝色沉淀生成，因此正确的答案选A。

点评：该题是高考中的高频题，属于中等难度的试题，试题侧重考查学生的能力。该题需要明确判断离子方程式正确与否的方法一般，即（1）检查反应能否发生。（2）检查反应物、生成物是否正确。（3）检查各物质拆分是否正确。（4）检查是否符合守恒关系（如：质量守恒和电荷守恒等）。（5）检查是否符合原化学方程式，然后灵活运用即可。该题有助于培养学生分析问题、解决问题的能力。

完形填空

Letting go of success
I want to make the most of every day. And, like most people, I've____ that the best way to do it is to let go of past failures. But that's not all. One can never fully ____ today while thinking too much about past successes, either. People never ____ while resting comfortably on their laurels (荣誉). The ___ is that sometimes our successes hold us back more than our failures!
I once ____ a story about the Oscar owner, actor Clark Gable. A friend ____ Gable one afternoon at the actor's home. She brought along her ____ son, who was playing happily with toy cars on the floor. He____ he was racing those cars around a great track, which in ____ was an imaginary circle around a golden statue (雕像). The small statue the boy played with was actually the Oscar Clark Gable ____ for his performance in the 1934 movie It Happened One Night.
When his mother told him the time had come to ____, the little boy asked the actor, “Can I have this?” ____ to the Oscar.
“Sure, ” he smiled. “It's yours.”
The horrified mother ____. “Put that back immediately!”
Giving the child the golden statue, Clark Gable said, “Having the Oscar around doesn't mean anything to me; ____it does.” The actor seemed to know that past success could be a ____ hammock (吊床) upon which he may be tempted to____, rather than a springboard setting him to begin a new start.
You may have learned to let go of past ____ and mistakes in order to free the present. But will you forget past successes and achievements in order to free the ____? Will your past be a springboard or a restful hammock?
“I like the ____ of the future better than the history of the past,” said Thomas Jefferson. I ____. After all, the future, not the past, is where the rest of your life will be lived.
小题1:A discovered B. inferred C. hoped D. worried

B．comfortable

A．difficulties

D．achievements

单项选择题

当室内冷负荷变化时，最简单又易达到效果的方法是______。

A．调节再热量
B．调节新风量
C．调节露点温度
D．调节送风量和新风量