人类生长和发育所需的能量有赖于绿色植物的

⑴图书馆在学校东偏北45°，1500米处．

⑵体育场在学校西偏北30°，2000米处．

⑶少年宫在学校南1750米处．

若关于x的不等式|x+1|﹣|x﹣2|＜a²﹣4a有实数解，则实数a的取值范围为（　　）

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                                                                                                                                 读(节选)  
                                                                                               人之一生．读之一生    读海，胸怀将变得辽阔
                                                                                               从春读到夏，从小读到大  读月，方知阴晴圆缺
                                                                                               读雨，方知万物可以滋润，心灵能够洗涤    

                                                                                               读日，便不再惋惜日近黄昏
                                                                                               读雪，能领悟到嚣的纯洁，感受到冬的春意             用心品读，细细感悟
                                                                                                读风，就能触摸d4)11的脉搏，聆听天地的呼吸      阴雨中能读出晴空
                                                                                               读霞，才能于苍茫中发现辉煌，展示自己韵不屈     枯黄中能读出翠绿
                                                                                               读花，你学会倾听     沙漠中能读出清泉
                                                                                               读树，你学套成长       黑暗中能读出晨曦
                                                                                               读山，你学会攀登                                     

                                                                                                                                                                                                                                          (诗歌有删改)

正要咬饵上钩的鱼，突然听到脚步声受惊逃走，鱼接收到声波的主要途径是（  ）