题目

先化简，再求值：，其中、满足． 答案：【答案】【解析】由题意原式去括号合并得到最简结果，利用非负数的性质求出x与y的值，代入计算即可求出值．原式，∵，∴，，则原式．情景七选五 请阅读下面一段对话，根据其情景，从下面方框内七个选项中选出能填入对话的五个选项。A：Good morning.1.B：Yes, I bought this jacket here last Sunday, but the colors ran when I washed it.2.A：Did you wash it in hot water?B：3.A：Did you leave it in water before you washed it?B：No, I didn’t do that, either.A：4.B：I would like you to give me my money back.A：The shopkeeper isn’t here.5.Why don’t you change it for another one?B：OK.I’ll have a look at the other jackets and try to choose one among them. 1.B 2.D 3.A 4.E 5.C 【解析】本对话内容是关于商场换货的情景。B上个星期天买了一件夹克，洗了以后，掉颜色，到商场去退钱，营业员说店主不在，可以换货。 1.句意：你好，我能帮你吗？ Can I help you?是口语中一句极为常用的句子(也可说 What can I do for you? 或 May I help you? 等)，广泛用于商店...