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题库 / Prep2007E2-DS-39
If c and d are integers, is c even?
(1) c(d + 1) is even.
(2) (c + 2)(d + 4) 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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【转载】(1)d+1是偶的时候，c可奇可偶，不能确定，NS
(2)d+4是偶的时候，c+2可奇可偶，则c可奇可偶，不能确定，NS
(1)+(2): 当d+1是奇的时候，条件1说明c得是偶数，同时满足条件2；当d+1是偶的时候，d就是奇数，所以d+4也是奇数，要想满足条件2，所以c+2得是偶数，说明c得是偶数。因此能确定c一定是偶数，S。
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