题目如下：
Are there exactly 3 distinct symbols used to create the code words in language Q?
1/ The set of all code words in language Q is the set of all possible distinct horizonal arrangements of one or more symbols, with no repetition.
2/There are exactly 15 code words in languages Q.
Answer: C. Both 1 and 2 together are sufficient.
请问以上条件中那句话说明了不能使用重复的symbol组合成code.
例如：若使用1，2，3来组成code.为什么不可以使用类似于11,22,33或者111，222，333？如果可以这样使用的话，我认为组合会多于15个。所以答案应该选E.
谢谢解答。 | 
