5 Simple Statements About Reo Music Explained
频率是单位时间内完成振动的次数,是描述振动物体往复运动频繁程度的量,为了纪念德国物理学家赫兹的贡献,人们把频率的单位命名为赫兹,简称“赫”。"These designs suggest that some types of psychological versatility decrease somewhat early in adulthood, but that the quantity of knowledge