[問題]GWD 01-10

[oneseven]

A set of numbers has the property that for any number t in the set, t+2 is in the set. If -1 is in the set, which of the following must also be in the set?

I. -3
II. 1
III. 5

A. I only
B. II only
C. I and II only
D. II and III only
E. I, II, and III

看不懂他題目的意思....還有可以順便給一下算式嘛
感激不盡

[eced]

題目是說一個集合裡有個特性如果t在集合裡,t+2也會在集合理
假如-1在集合裡,選項那些也會在集合裡?
t=-1, t+2=1
t=1, t+2=3
t=3,t+2=5
所以答案是D

至於-3是不是在集合裡,無法推出
不能用t+2=-3去推 t=-5
題目沒說 t+2存在,t也存在集合裡