X、Y、Z、M、N代表五种金属，有以下反应：
①Y与M用导线连接放入稀硫酸中，M上冒气泡；
②M、N为电极，与N的盐溶液组成原电池，电子从M极流出，经过外电路，流入N极；
③Z+2H2O(冷水)=Z(OH)2+H2↑；
④水溶液中，X+Y2+=X2++Y。
则这五种金属的活动性由强到弱的顺序为（ ）
A．Z＞X＞Y＞M＞N
B．Z＞Y＞X＞M＞N
C．Z＞X＞Y＞N＞M
D．X＞Y＞M＞N＞Z
答案：A
题目分析：①Y与M用导线连接放入稀硫酸中，M上冒气泡；证明M为原电池是正极，所以活动性Y＞M；②在原电池反应中，电子流出的电极为负极，电子流入的电极为正极，由于电子从M极流出，经过外电路，流入N极，所以活动性M＞N；③Z+2H2O(冷水)=Z(OH)2+H2↑。证明Z的活动性很强。在题目提供的所有的元素中是最强的。④水溶液中，X+Y2+=X2++Y，则证明活动性X＞Y。所以这五种金属的活动性由强到弱的顺序为Z＞X＞Y＞M＞N 。选项为A。
A hot dog is one of the most popular American food. It was named after frankfurter, a German food. You may hear “hot dog” ___16___ in other ways. People sometimes __17___ “hot dog” to express pleasure(快乐). For example, a friend may ask ___18___ you would like to go to the cinema. You might say, “Great. I’d love to. ” Or, you could say,”__19____! I’d love to go.” People ___20__ use the expression to describe someone who is a “show-off”, who tries to show everyone else how ___21__ he is. You often hear such a(n) ___22__ called a “hot dog”. He may be a basketball player, for example, who __23____ the ball with one hand making a(n) __24__ catch seem more difficult. You know he is a “hot dog” because when he makes such a catch, he bows(鞠躬) to crowd, hoping to __25___ their cheers.
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