Q9:

If n and t are positive integers, is n a factor of t?

(1) n = 3^n-z

(2) t = 3ⁿ

^{答案给的是C，可是t/n=}3^{z，而题目并没有说z是正整数呀，如果z=1/2，那么也能保证n是t的因子吗?是不是我对因子（factor）的定义有点模糊？请NN们指教！}