题目

Silk production has a long and colourful history unknown to most people. Scientific discoveries have shown that silk production existed in China from around 2500 B.C., although it could be much older. For hundreds of years, China kept the secret of silk to itself as one for the most closely protected secrets in history. Anyone revealing the secret of silkworms or trying to take silkworm eggs out of ancient China was punished by death. At one time silk was reserved only for the Chinese emperor. Gradually, others began wearing silk. In addition to being used for clothing, silk came to hav点P（2，－3）关于x轴的对称点的坐标是____________．