话题语篇导读

Along with silk and paper，gunpowder is another invention by Chinese and the Silk Road helped it spread to the West.The dating of gunpowder is as early as 850 AD.The Chinese used gunpowder to make fireworks and for signal flares.Gunpowder was also thought to have been used in medicine and in alchemy. This invention seems to have been discovered in China by accident—by alchemists when doing experiments. The gunpowder used for military purpose was first recorded in 919 AD.By the 11th century，explosive bombs filled with gunpowder were introduced and used in China.The words “fire cannon”“rocket” and “fireball” appeared time and again in the official Song history as well as two other books written during the same period.