题目

已知a2﹣2a﹣1＝0，则a4﹣2a3﹣2a+1等于（   ） A．0                           B．1                           C．2                           D．3 答案：C 【解析】 ∵ ，∴ ，原式= = = =2． 故选C．The train_________at seven o’clock. You’d better get to the station by half past six.A. is about to start B. is due to startC. is due to starting D. owes to start