Gwd-19-Q22:
A researcher plans to identify each participant in a certain medical experiment with a code consisting of either a single letter or a pair of distinct letters written in alphabetical order. What is the least number of letters that can be used if there are 12 participants, and each participant is to receive a different code?
A. 4
B. 5---答案
C. 6
D. 7
E. 8
我选的是A。我觉得关键在于对in alphabetical order的理解,恳请大家帮忙,谢谢
A的话只能表示10个人阿,
5个字母的话, C51+C52=15, 最多可以表示15人,所以这里至少要用5个字母。
汗,咬文嚼字阿,哈哈。
我的理解,in alphabetical order就是有先后顺序的意思,那么a跟b的话,
就只能取ab, 而不能取ba, ok?
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