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题库 / Prep2007E1-DS-183
The positive integers x, y, and z are such that x is a factor of y and y is a factor of z. Is z even?
(1) x is even.
(2) y is even.
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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假设X和Y分别是奇数和偶数的情况即可发现，要是XZ为偶，且X为Z因数，X和Y必定同为偶数。