打开知识的钥匙．是持之以恒的努力。年近50岁的华北油田采油一厂干部李明招，经过十个春秋的刻苦自学，取得了汉语言文学本科毕业证书的学士学位，并在工作中取得了可喜的成绩。问其成功的秘诀，李明招不无感慨地说：“挤劲加韧劲，使我跨过了一沟又一坎，领略到了险峰上的无 Open the key to knowledge. Is a sustained effort. Li Mingzhao, a cadre of the first oil production plant of Huabei Oil Field, nearly 50 years of age, has obtained a bachelor’s degree in Chinese language and literature after ten years of hardworking and self-study and has made gratifying achievements in his work. Asked the secret of his success, Li Mingzhao said without hesitation: "squeeze tenacious, so I crossed a ditch and a ridge, a taste of the risk peak