“AIST”Tools—Make Work Efficient
1.Gold: red and yellow precious minerals, international monetary standard
2. Silver: it is a kind of transition metal. The chemical symbol Ag. Silver is one of the metals known and used in ancient times. It is an important precious metal.
3. Copper: one of the earliest metals used by human beings. It is a metal in the earth's crust and oceans.
4. Iron: it accounts for 4.75% of the crustal content, ranking the fourth in the crustal content after oxygen, silicon and aluminum.
5.Tin: tin has been found and used since ancient times. In some of the ancient tombs in China, they often found some tin pot, tin candlestick and other tin ware.