Anyone mon and unattractive in our life, yet it has played an important role in our study, Our teachers have mon rectangular blackboard, but it is the golden key to the door of the treasure house of knowledge.
黑板在生活中是司空见惯的，然而却在我们的学习中起着重要作用。老师在黑板上写下一个又一个的方程，解决了无数难题。就这样一个普通的长方形黑板，可却是通往知识宝库的金钥匙。