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题库 / Prep2007E1-DS-128
The points A, B, C, and D are on a number line, not necessarily in that order. If the distance between A and B is 18 and the distance between C and D is 8, what is the distance between B and D ?
(1) The distance between C and A is the same as the distance between C and B.
(2) A is to the left of D on the number line.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
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不仔细易错选C
思考的时候，出现了思维的bug
因为ABCD的相对位置是不固定的，所以不能按照 AB和CD两条线段的移动 的思路去分析。
条件1只能得出C的位置在AB的中间 并不能确定D的位置的情况，所以1单独不充分。