the more careful you are,the fewer mistakes you will make in the test.careful为什么不能用carefully

题目

the more careful you are,the fewer mistakes you will make in the test.careful为什么不能用carefully

答案

这里,careful是are的表语,故用形容词；
若are改成study,则相应的careful要改成副词carefully做状语,the more carefully you study,
希望这样有助理解