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题库 / GMATAdvanced-PS-6
The letters C, I, R, C, L, and E can be used to form 6-letter strings such as CIRCLE or CCIRLE. Using these letters, how many different 6-letter strings can be formed in which the two occurrences of the letter C are separated by at least one other letter?
96
120
144
180
240
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捆绑法
A66/A22 - A55 = 240
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