从10个英语字母A、B、C、D、E、F、G、X、Y、Z中，任选5个字母组成一个“词”（字母允许重复），将所有可能的“词”按辞典顺序（即英汉辞典中英语词汇的排列顺序）排列，得到一个“词表”：AAAAA，AAAAB，AAAAC，…，AAAAZ，AAABA，AAABB，AAABC，…，AAABZ，…，ZZZZY，ZZZZZ如果设位于“词”CYZGD与“词”XEFBA之间（这两个词除外）的“词”有k个，那么“词表”中的第k个词是______．
设A为0，B为1，C为2…Z为9，则CYZGD是28963，XEFBA是74510，所以XEFBA-CYZGD=74510-28963=45547；
所以K是45547-2=45545，
所以第k个词是EFFEF，
故答案为：EFFEF．
| 完形填空。 | ||||
| Have you ever seen a rainbow (彩虹) in the sky? Do you know what it is? A story says that when you see a rainbow you should 1 at once to the place where it touches (触摸) the ground, and 2 you would find a bag of gold. Of course, it is not 3 . You could not find the bag of gold, nor could you ever find its end. No matter how 4 you run, it always seems far away. A rainbow is not a thing which we can feel with our 5 as we can feel a flower. It is only the effect (效果) of light shining on raindrops (雨滴). The raindrops catch the sunlight and break it up into all the wonderful colors which we see. It is 6 a rainbow perhaps because it is made up of raindrops and looks like a bow (弓). That is 7 we can never see a rainbow in a clear 8 . We see rainbows 9 when there is rain in the air and the sun is shining brightly through the clouds. Every rainbow has many colors in the same order. The first of the top color is always red, next 10 orange, then green, and last of all blue. A rainbow is indeed one of the wonders of nature. | ||||
|