“自然选择学说”可以解释生物进化的原因，它的提出者是（  ）

若$m-\frac{1}{2}<x\le m+\frac{1}{2}$（其中$m$为整数），则称$m$为离实数$x$最近的整数，记作$\left\{x\right\}$，即$\left\{x\right\}=m$.设集合$A=\left\{\left(x,y\right)|y=x-\left\{x\right\},x\in R\right\}$，$B=\left\{\left(x,y\right)|y=a{x}^2+bx,x\in R\right\}$，若集合$A\cap B$的子集恰有两个，则$a,b$的取值不可能是（    ）

某同学利用“多米诺骨牌”效应，设计了如图气体制取与性质验证的组合实验，打开A中分液漏斗的活塞，很快看到E中导管口有气泡冒出，且溶液由紫色变红色．请看图回答问题：

      An Englishman was showing a foreign visitor around London. “What’s that strange building?” asked the visitor. “That's the Tower of London.” “I see. How long did it take to build it?” “About 500 years.” “In my country we can build it in five months,” Shortly after that they came to St. Paul's Cathedral(大教堂). “Very interesting!” said the visitor. “How long did it take to build it ?” “Near forty years.” said the Englishman. “In my country we can finish it in forty days at most,” said the visitor. This went on all day.
      They visited most of the best known buildings in the city. Every time they saw a new one, the visitor asked what it was and how long it took to build it. Then he said that they could do the same thing much faster in his country.
      At last the Englishman got angry with the visitor though he tried not to show it. Several days later they came to the House of Parliament(议会)and the visitor asked his usual question, “What is that?” The Englishman answered, “ I have no idea. It wasn't there last night.”

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