A:①②③④
B:②③④
C:①③④
D:①②④
某同学用盐酸与氢氧化钠按照如图的方式进行中和反应实验.
—In order to give more chances to the talented students, an dancing competition ______ soon.
—That's great!
读图所示邮票,该邮票所反映的历史重大事件标志着( )