The previous page is sending you to http://drhuang.com/chinese/science/chemistry/book/%E7%94%9F%E7%89%A9%E5%8C%96%E5%AD%A6%E4%B8%8E%E5%88%86%E5%AD%90%E7%94%9F%E7%89%A9%E5%AD%A6/457.htm.

 If you do not want to visit that page, you can return to the previous page.