题目

若式子有意义,则化简|1-x|+|x+2|=____. 答案：【答案】2x+1【解析】先根据题意得出x的范围，在进行化解.由题意得:x＞1∴1－x＜0,x＋2＞0;∴|1－x|＋|x＋2|＝x－1＋x＋2＝2x＋1故答案为2x＋1.With a history of more than 1,400 years, Zhaozhou Bridge is the ________ stone arch bridge in the world.A.oldB.olderC.oldestD.elder