SAT句子改错题

题目

SAT句子改错题
Since some people are convinced that dowsing,a method of finding underground water with a Y-shaped stick,is effective,but others condemn the procedure as mere superstition.
答案是since some,为什么?要怎么改

答案

since 一般用做引导原因状语从句,后面直接加主句.比如：since you are ill,you don't have to take my class.
而这句话后面用But转折,变成了前后不同的两个分句的并列,与前面矛盾.显然不合语法逻辑.
所以可以把since 去掉.