题目

甲和乙同时从A地出发，匀速行走到B地．甲走完一半路程时，乙才走了4千米．乙走完一半路程时，甲已走了9千米．当甲走完全程时，乙未走完的路程还有__________千米 答案：【答案】4【解析】可设全程为2S，以及两个人的速度分别为x，y．等量关系为：甲走全程一半的时间=乙走4千米用的时间；乙走全程一半的时间=甲走9千米用的时间，把相关数值代入化简可得路程的一半长，进而求得全程长，进而可求乙未走完的路程长．解：设全程为2S千米，甲速度为x千米/时，乙速度为17．The Amber Room was first designed as a palace for Frederick I．When first finished，it was in the fancy（76）style and was decorated（77）with gold and jewels．Then the next king of Prussia，Frederick William I，gave it to Peter the Great as a gift．In return（78），he was given a troop of soldiers．The room served（79）as a small reception hall at that time．After that，Catherine II，asked her artists to add more details（80）to the Amber Room，which made it one of the wonders（81）of the world．Later，the Amber Room belonging（82）to Katherine was missing and it was said to have been stolen by German Nazi．However，what happened to the Amber Room remains a mystery（83）．Recently，the Amber Room has been rebuilt（84）by the artists by studying old photos of the former one．It was made to celebrate（85）the 300th birthday of the city of St Petersburg．