X、Y、Z三种金属中，只有Z不能和稀盐酸反应；将Y放入X的化合物溶液中，Y表面有X析出。则X、Y、Z三种金属的活动性顺序为 ( )
A．Z>Y>X
B．Y>X>Z
C．Y>Z>X
D．X>Z>Y
答案：B
X、Y、Z三种金属中，只有Z不能和稀盐酸反应，说明在金属活动顺序中，X、Y都位于H之前而Z位于H之后；将Y放入X的化合物溶液中，Y表面有X析出，可得Y的活动性比X强；
综合以上分析，X、Y、Z三种金属活动性由强至弱的顺序为Y＞X＞Z；
故选B．
| 从方框中选择恰当的句子完成下面的对话。 | |
| A: The south tigers may become extinct (灭绝的) within 30 to 50 years if it does not receive protection. B: 1______ A: There are 20 to 30 South China tigers. Guangdong Province has only five left because forests are being destroyed. B: 2______ A: The life span of the South China tiger is 20 to 25 years, but the tigers breed (繁殖) and the survival rate (成活率 for cubs (小虎) is poor. B: Why not clone (克隆) the tiger? A: It's not that easy. 3______ B: What would happen in the future? A: Well, I'm afraid we may not have this kind of animal at all in the 21st century without hard work and help from the scientists. B: 4______ A: Yes. I hear that the scientists are trying there best to save the tigers, including (包括) the Northeast tigers. B: 5______ A: I think so.
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