I would have come earlier, but I ________ that you were waiting for me.

A．didn’t know

B．hadn’t know

C．would have known

D．haven’t known

仅有高中学历辽宁省锦州市下岗职工、三轮车夫蔡伟刻苦自学，被录取为复旦中国语言文学系中国古典文献专业2009级博士研究生，对此，下列说法不正确的是[ ]

A．学习是成才的阶梯     

B．不断学习，不断进步，应是我们一生的追求

C．逆境是成才的最佳环境 

D．成才的关键是靠自己的勤奋努力和不懈奋斗