若方程组$\left\{\begin{array}{c}ax+by=3\\ 2ax+by=4\end{array}\right.$与方程组$\left\{\begin{array}{c}2x+y=3\\ x-y=0\end{array}\right.$有相同的解，则a、b的值分别为（　　）

①活性碳②过氧化钠③氯水④漂白粉⑤臭氧．

阅读下面这首古诗，完成小题。
                                                                                     夏日西斋书事
                                                                                        宋•司马光
                                                                       榴花映叶未全开，槐影沉沉雨势来。
                                                                       小院地偏人不到，满庭鸟迹印苍苔。
【注】在熙宁变法中，司马光与主持变法的王安石发生严重分歧，在政见不同、难于合作的情况下，司马光被迫辞官，退居洛阳。

   Flags have existed for over 3,000 years. The earliest flags were wooden or metal poles with a carving. About 2,000 years ago pieces of fabric were added to some poles for decoration. Over the next 500 years the free-flying part of the flag became more important.