题干

为了迎接2010年广州亚运会,某大楼安装5个彩灯,它们闪亮的顺序不固定,每个彩灯彩灯闪亮只能是红、橙、黄、绿、蓝中的一种颜色,且这5个彩灯所闪亮的颜色各不相同.记这5个彩灯有序地闪亮一次为一个闪烁,在每个闪烁中,每秒钟有且仅有一个彩灯闪亮,而相邻两个闪烁的时间间隔均为5秒。如果要实现所有不同的闪烁,那么需要的时间至少是(  )

A:1205秒

B:1200秒

C:1195秒

D:1190秒

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答案(点此获取答案解析)

C

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    Liverpool, my hometown, is a special city. It is so unique that in 2004 it became a World Heritage(遗产)Site.

    I recently returned to my home city and my first stop was at a museum on the River Mersey. Blanketed in mist(薄雾),Victorian architecture rose from the banks of the river, responded to the sounds of sea-birds, and appeared unbelievably charming. When I headed toward the centre, I found myself surrounded by buildings that mirror the best palaces of Europe. It is not hard to imagine why, on first seeing the city, most visitors would be overpowered by the beauty of the noble buildings, which are solid signs of Liverpool's history.

    As if to stress its cultural role, Liverpool has more museums and galleries than most cities in Britain. At Walker Art Gallery, I was told that it has the best collections of Victorian paintings in the world, and is the home of modern art in the north of England. However, culture is more than galleries. Liverpool offers many music events. As Britain's No. 1 music city, it has the biggest city music festival in Europe, and its musicians are famous all over the world. Liverpool is also well-known for its football and other sports events. Every year, the Mersey River Festival attracts thousands of visitors, making the city a place of wonder.

    As you would expect from such a city, there are restaurants serving food from around the world. When my trip was about to complete, I chose to rest my legs in Liverpool's famous Philharmonic pub(酒馆). It is a monument to perfection, and a heritage attraction itself.

    Being a World Heritage Site, my home city is certainly a place of “outstanding universal value”. It is a treasure house with plenty of secrets for the world to explore.