一道SAT数学题
If a,b,and c are different positive integers such that a is divisible by b,and b is divisible by c,which of the following statements must be true?
1.a is divisible by c.
2,a has at least 3 positive focators
3.a=bc
我就想问下第二个,是不是一个数的约数（或叫因数,factor)是包括这个数本身和1,那也就是说一个数至少有2个约数,另外,约数总是偶数个,（高中后小学有的概念就记不清了,晕.没想到SAT里能考到）