在一定条件下,2NO+O2=2NO2达到平衡的标志是( )
A. NO,O2,NO2分子数目比是2:1:2
B. 反应混合物中各组分的物质的量浓度相等
C. 混合气体的颜色不再变化
D. 混合气体的平均相对分子质量改变
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恒温恒压下,当一个反应的标准摩尔吉布斯自由能变为5 kJ·mol-1,该反应( )
A. 能正向进行
B. 能逆向进行
C. 不能判断
D. 不能进行
Why was the little boy disappointed?
A. He couldn’t get a football shirt from Messi.
B. His family was too poor to buy him a football.
C. He couldn’t get a football shirt to look like Messi.
D. His family cannot afford to pay forfootball lessons.
Why did the shirt made by his brother become popular?
A. The shirt appeared on Facebook.
B. The shirt fit the little boy perfectly.
C. The shirt had blue and white lines on it.
D. The shirt had Messi’s name and number on it.
What made the little boy feel happy later?
A. His picture became very popular on the Internet.
B. Messi met the boy and gave him a football shirt.
C. He knew he could meet Messi somedayvery soon.
D. He got a real football shirt with Messi’s signature.
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