20个数复式三中三有多少组

简介：The so-called wooden scale is a small weighing instrument with a wooden or metal pole with star points and tapers as the main body, and is equipped with a weight, a weight rope and a scale pan. According to the scope of use and the size of the scale, it is divided into three types: pan scale, pan scale and hook scale. A steelyard is a first-class arm lever, a simple weighing instrument that uses the principle of lever balance to weigh weight.