关于声现象，下列说法正确的是（）

给下列图片排序。    There are some special days in a year.New Year's Day is in January.Then Tree Planting Day comes after Women's Day.Children like June best.Because Children's Day is in June.Dragon Boat Festival (端午节) always comes after Children's Day.I like Children's Day，because I can play many games and get some gifts from my parents on that day.In September we have Teachers' Day.And in October，we have China's National Day.
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一个几何体的三视图如图所示．已知这个几何体的体积为8，则h=（   ）

某班在进行主题学习时，同学们利用互联网收集到以下资料：“上甘岭战役”“最可爱的人”“朝鲜停战协定”。据此推断他们研究的主题是（    ）

老花镜的“度数”等于它的焦距的倒数乘100，请设计一个测老花镜度数的简单方法，要求写出所用器材、操作步骤和计算公式。