逻辑推理题目做起来似乎很麻烦，因为有一大堆的逻辑。本文为您介绍图形解法。
题目 Problem:
A number of spicies faced erxtinction during the mesozoic era. Species R,S,T,U,V,W, and X were speciess that all become extinct dutring this era. and scientist have determined that therir extinctions occured based on the following constraints:
W before X
U after T
S before T
X before U
V after U
S before W
R before S
Let us get their condition diagram:
将上面能合并的条件图合并, 得到两个条件:
图1
注意这两个条件图的每个条件只是表明了图中间元素之间的次序关系。 不同图之间的有些元素,如 T, 和 W, X,之间的次序关系我们没有得到,所以还不能合并成一张图。
Q1. Which were the last two species to go to extinct?
A) X,V
B) T,U
C) X,U
D) U,V
E) R, S
从条件图直接得出答案是 D) U,V。
Q2。 Which species could have been fourth one to go extinct?
A) S
B) V
C) U
D) W
E) R
从图看出,前两位是R, S, 后两位是 U, V,所以答案只能是 D) W 。
Q3. Which is the smallest number of species that could have benn gone extinct before T?
A) two
B) There
C) Four
D) Five
E) Six
从 Q2 分析知道, 前两位是R, S, 后两位是 U, V, 而 T, W, X之间的关系未明, 所以答案是A) two。
Q4. Which of following must be true of X were extinct after T?
A) two species went extinct before T
B) There species went extinct before T
C) Four species went extinct after T
D) Five species went extinct before T
E) At least there species went extinct after T
画出新加的条件图。 ;
跟初始条件合并:
分析: W 可以在 T 之前, 也可以在 T 之后, 而 X,U,V 已经肯定在T 之后,所以答案是 E) At least there species went extinct after T。
Q5. How many possible orders are there for the species extinction pattern?
A) One
B) Two
C) Three
D) Four
E) Five
分析:回到图1 ,我们看见只有 T,和 W, X 的关系没有确定, 而T 可以在 W, X 周围去任意的三个位置,所以答案是 C) Three
