4，10，8，17，12，（ ），16，31 A. 14 B. 15 C. 23 D. 24

To solve the sequence 4, 10, 8, 17, 12, ( ), 16, 31, we can split it into two interleaved subsequences by separating terms at odd and even positions.

Step 1: Analyze the odd-position subsequence

Terms at positions 1, 3, 5, 7: 4, 8, 12, 16.

The pattern here is straightforward: each term increases by 4 (4 + 4 = 8, 8 + 4 = 12, 12 + 4 = 16).

Step 2: Analyze the even-position subsequence

Terms at positions 2, 4, 6, 8: 10, 17, ?, 31.

We need to find the term at position 6 (the third term in this subsequence).

Calculate the differences between consecutive terms:

From 10 to 17: \(17 - 10 = 7\).

Assuming a consistent increment, the next term would be \(17 + 7 = 24\).

Verify with the final term: \(24 + 7 = 31\), which matches the 8th term in the original sequence.

Thus, the missing term (at position 6) is 24.

Answer: D.24

Does this pattern remind you of how interleaved sequences often hide simple linear trends? Next time you encounter a confusing sequence, try splitting it into odd/even subgroups—you might uncover two straightforward patterns instead of one complex one.