求大牛解释 GWD3-Q20

optic82

GWD3-Q20:
ShippingClerk:  The five specially orderedshipments sent out last week were sent out on Thursday.  Last week, all of the shipments that weresent out on Friday consisted entirely of building supplies, and the shippingdepartment then closed for the weekend. Four shipments were sent to Truax Construction last week, only three ofwhich consisted of building supplies.

Ifthe shipping clerk’s statements are true, which of the following must also betrue?

1. At least one of the     shipments sent to Truax Construction last week was specially ordered.
   

At least one of last     week’s specially ordered shipments did not consist of building supplies.

At least one of the     shipments sent to Truax Construction was not sent out on Thursday of last     week.

At least one of the     shipments that were sent out on Friday of last week was sent to Truax     Construction.

At least one of the     shipments sent to Truax Construction last week was sent out before Friday.
给出的解释是
lawyer_1
A。错。原文看不出Fourshipments to Truax Construction last week 和第一句的five specially ordered shipments 有何关系。错


B。错。因为不知道上周四的SHIPMENT中是否包括SUPPLIES，只知道周五的都有。故不知T周四送出的 five specially ordered shipments 是否有SUPPLIES。

C。错。周四送多少去TruaxConstruction ，或有没有送，原文不知道。

D。错。原文只知道去TruaxConstruction 有四个，至于何时送，不知道。尽管原文说这四个中，有三个有SUPPLIES，而周五送的都有SUPPLIES，但不知其他时间送的是否也有SUPPLIES，所以不知这三个是否都是周五送。

E。对。周五的都有SUPPLIES，以后就关门了，所以没有SUPPLIES的肯定是周五前送的。即去Truax Construction 中肯定有一个是周五前送的。又因为可能周五前的其他时间送的也包括SUPPLIES，即另外的三个也可能是周五前送的，所以E用“ATLEAST ONE”

http://forum.chasedream.com/dispbbs.asp?BoardID=24&ID=65416


但是我还是看不明白啊，求大牛解释，感激～～～

lkhs518

你哪里看不明白呢

VincentShu

题目中有四个条件：
1、5艘OS礼拜四出发。（没有说只有这些是OS的）
2、星期五出发的船把全部有BS。（就是说，星期五出发的一定都有BS，但是有BS的不一定是星期五出发的。）
3、有四艘船到了TC，只有三艘是有BS的。
4、礼拜五之后就没有船出发了。（the shipping department then closed for the weekend）
（注意：上述条件的船是可以重合的，如：有一艘船是OS的，又是装了BS的，也到达了TC）

A。至少有一艘到达TC的船是OS的。（这些船可以都不是OS的）
B。至少有一艘OS的船不含BS。（可以一艘都没有，如：星期五出发的都是装有BS（限定）但是没有OS的）
C。至少有一艘到达TC的船不是礼拜四出发的。（首先装BS的三艘肯定不是，其次还有一艘可以剩下的任意一天出发，不一定是礼拜四）
D。至少有一艘星期五出发的船是去TC的。（也可以一艘都没有）
E。至少有一艘到达TC的船是礼拜五前出发的。（很明显，星期五出发的都是有BS的。所以剩下一艘可以星期五之前的任何一天出发，同C）

感觉排除法应该是最好考虑，也最保守的方法吧，must be ture问题方法欢迎讨论！