探讨一道逻辑

xiahuistacy

Shipping Clerk:  The five specially ordered shipments sent out last week were sent out on Thursday.  Last week, all of the shipments that were sent out on Friday consisted entirely of building supplies, and the shipping department then closed for the weekend.  Four shipments were sent to Truax Construction last week, only three of which consisted of building supplies.

If the shipping clerk’s statements are true, which of the following must also be true?

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

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

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

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

E.       At least one of the shipments sent to Truax Construction last week was sent out before Friday.

这个题目怎么做啊  完全没有头绪  答案是E

tangyp

是E啊，这里有三个命题：
specially ordered           Thursday
Friday                            entirely of building supplies
to Truax Construction   only 3 with building supply (the other not)
所以，to Truax Construction 至少有一个（the other）不是在Friday（因为Friday的entirely of building supplies）