题目

 The boy climbed into the third storey of the building, from _____ he could look farther into   the distance.  A. which            B. it           C. there           D. where 答案：D根据题意解答（1）若f（x）=|x﹣1|+|x﹣4|，求不等式f（x）≥5的解集；（2）若g（x）=|x﹣1|+|x﹣a|（a∈R）且x∈R使得f（x）≤4成立，求a的取值范围．