the question is so difficult that only ____students can work out it 选few 还是a few

题目

the question is so difficult that only ____students can work out it 选few 还是a few
老师不是说so...that句型中后表否定吗，那应该用few

答案

a few 有几个
翻译：这个问题如此的难,只有几个学生能算出来
而 few 几乎没有,不能和only搭配