有X、Y、Z三种金属单质，将它们分别放入稀盐酸溶液中，只有Y能发_爱下问搜题

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问题填空题

有X、Y、Z三种金属单质，将它们分别放入稀盐酸溶液中，只有Y能发生反应产生无色气体，将X和Z分别放入硝酸银溶液中只有Z表面有银白色的金属银析出，则X、Y、Z三种金属的活动性由强到弱的顺序是______．

答案

在金属活动性顺序中，位于氢前面的金属能置换出酸中的氢，X、Y、Z三种金属单质，将它们分别放入稀盐酸溶液中，只有Y能发生反应产生无色气体，说明Y的位置排在氢的前面，X、Z的位置排在氢的后面；即Y＞H＞X、Z．

活动性强的金属能把活动性弱的从它的盐溶液中置换出来，将X和Z分别放入硝酸银溶液中只有Z表面有银白色的金属银析出，说明Z的活动性比银强，X的活动性比银弱，即Z＞Ag＞X．

综上所述：X、Y、Z的金属活动性由弱到强的顺序是Y＞Z＞X．

故答案为：Y＞Z＞X．

完形填空

I grew up poor – living with six brothers, my father and a wonderful mother．We had   26 money and few worldly goods, but plenty of love and attention．I was   27   and energetic．I understood that no matter how poor a person was, they could   28   afford a dream．
My dream was to be a   29 ．When I was sixteen, I could crush a baseball, throw a ninety – mile – per – hour fastball．I was also   30 : my high – school coach was Ollie Jarvis, who   31 me the difference between having a dream and showing strong belief．One particular   32 with him changed my life forever．
It was a summer and a friend recommended me for a summer 33 ．This meant a chance for my first income – cash for a new bike and new clothes, and the   34 of savings for a house for my mother．The opportunity was attracting, and I wanted to   35   at it．
Then I realized I would have to   36   summer baseball to handle the work schedule, and that meant I would have to tell Coach Jarvis I wouldn’t be playing．I was   37   about this．
When I told Coach Jarvis, he was as 38 as I expected him to be．“You have your whole life to work,” he said．“Your   39 days are limited．You can’t afford to waste them．”
I stood before him with my head   40 , trying to think of how to explain to him why my dream of buying my mom a house and having money in my pocket was worth 41   his disappointment in me．
“How much are you going to make at this job?” he demanded．
“$ 3．25 an hour,” I replied．
“Well, is $ 3．25 an hour the price of a   42 ?” he asked．
That   43 laid bare for me the difference between wanting something right now and having a goal．I devoted myself to   44   that summer, and within the year I was offered a $ 20,000 contract．I signed with the Denver Broncos in 1984 for $ 1．7 million, and bought my mother the   45 of my dreams．

D．disappointed

D．discouraged

单项选择题

循环经济：本质上是种生态经济，它要求运用生态学规律而不是机械论规律来指导人类社会的经济活动，特征是低开采低排放高利用。
下列不属于循环经济做法的是( )。

A．变单程式经济为循环式经济
B．变消耗型经济为休养生息型经济
C．变储备型经济为增长性经济
D．退田还湖，退耕还林