[求助]gmatprep里一道题

sherry777

For a finite sequence of nonzero numbers, the number of variations in sign is defined as the number of pairs of consecutive terms of the sequence for which the product of the two consecutive terms is negtive. what is the number of variations in sign for the sequence 1, -3, 2, 5, -4, -6

A.1

B.2

C.3

D.4

E.5

题意不理解，请教大家

yoyo0327

题目就是给了个定义

定义the number of variations in sign 是相邻两个数的乘积是负数的对数

具体到这题就是:1*-3<0  -3*2<0 　2*5>0 　5*-4<0 -4*-4>0

               共有三对数的乘积是负数，所以答案是３