题目

从方框中选句子，把下列对话补充完整。A: Wow.___________________!B: What can you see?A:_______________________.B:_______________________?A:No, there isn't.________________.A. I can see a big panda.B. Is there a monkey.C. This is cool!D. But there are two snakes. 答案：【答案】1.C 2.A 3.B 4.D 【解析】略1．在化合物X2Y和YZ2中，Y的质量分数分别为a和b，则在化合物X2YZ3中Z的质量分数为$\frac{3a（1-b）}{3-b}$．