ＧＲＥ全真考試題八

　There will be seven performers in a talent show: a guitarist, a hypnotist, a juggler, a magician, a pianist, a singer, and a ventriloquist. Exactly three of the performers—the guitarist, the pianist, and the singer—will each require a recorded musical accompaniment. The schedule for the show has seven consecutive time slots. Each of the seven performers will appear in exactly one time slot, and each time slot will have exactly one performer appearing in it. The schedule must follow the rules below:　

　　The juggler must appear first.

　　The ventriloquist cannot appear immediately after the magician.

　　At most two performers requiring a recorded musical accompaniment can appear　in succession.

　　Which of the following is an acceptable schedule for the last four performers in the show?

　　Fourth Fifth Sixth Seventh

　　Juggler Hypnotist Guitarist Pianist

　　Guitarist Magician Ventriloquist Singer

　　Magician Pianist Singer Guitarist

　　Singer Guitarist Pianist Hypnotist

　　Ventriloquist Hypnotist Magician Singer

　　答案：(E)

　　這是一道非常簡單的排列題，但是分析題在于你會不會做，而在于你花了幾分鐘把它做完，在于速度。我們通過講解幾道題來體會一下如何迅速定位答案。

　　讀題：7個表演者g,h,j,m,p,s,v參加表演，其中3個g,p,s有音樂伴奏。有7個位置，一人一個。

　　寫條件：

　　1、j=1 (表示j在第一個位置)

　　2、～mv (表示v不能出現(xiàn)在m的后面)

　　3、～(gps) (表示需要音樂伴奏的3人中最多只有2人連續(xù))

　　條件總結(jié)：

　　**注意g.p.s為等價元素（當(dāng)然，如果在問題中又出現(xiàn)新的限制條件后，就不一定是）

　　If the ventriloquist appears third, the singer appears fifth, and the pianist appears sixth, which of the following must be true?

　　The guitarist appears second.

　　The guitarist appears fourth.

　　The hypnotist appears second.

　　The magician appears fourth.

　　The magician appears seventh.

　　答案：(A)

　　If the singer appears third and the pianist appears fourth, the guitarist must ap