Julian had five indoor potted plants, each of which - in order to survive - only needed to be watered once in a certain number of days

题目

Julian had five indoor potted plants, each of which - in order to survive - only needed to be watered once in a certain number of days. That number was not the same for all five plants. Julian last watered the plants - all of them - at noon on a Monday. He left home that Thursday and returned the following Thursday at noon. None of the plants were watered while Julian was away, and none of them died from any cause except lack of watering. At least one plant was alive when Julian returned. How many were alive in all?

(1) Exactly two plants were such that they would have survived only if Julian had watered them on the day he left home.

(2) Three plants were identical in terms of watering needs.

选项

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.

解析

我们知道Julian在周一中午给植物浇了水，然后在周四出发离家一周。我们还得知，他离开期间至少有一株植物存活了下来。我们的任务是确定确切有多少株植物存活了。 **(1) 恰好有两株植物，只有在Julian离家那天（周四）给它们浇水的情况下，它们才会存活。** 这句话表明，这两株植物只有在周四被浇水才能存活。这意味着这两株植物在Julian缺席期间没有存活，因为周四那天并未给水。但除此之外，可能还有其他植物——比如另外一株，由于它对浇水频率的要求比这两株更高，同样无法存活。也有可能，只有这两株没能存活，其余三株都活了下来。 **（条件不充分）** **(2) 有三株植物在浇水需求方面是完全相同的。** 如果这三株需求相同的植物中包含了那株存活下来的植物，那么至少会有三株植物存活。但我们并不知道确切有多少存活，因为有可能另外两株植物对浇水频率要求更低，它们也同样活了下来。 **（条件不充分）** **(1)+(2) 结合(1)中“恰好两株植物具有那种特殊生存条件”的表述，来自(2)的那三株需求相同的植物不可能包含这两株死亡的植物。** 因此，这三株需求相同的植物必须包含那株唯一存活下来的植物，从而这三株植物全部存活。 **（条件充分）** **答案：C。**

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