a few of是单数还是复数

题目

a few of是单数还是复数
only a few of the choir doesn't know the words to the song 是对的还是错的
（出自language & sentence skills second course practice /page160）
速度的说……我快急死……

答案

当然不对啦
因为few只能修饰可数名词.
它有两种词组：a few of和few of
a few of:少许,少数（有一些）
few of:少许,少数（几乎没有）
都是修饰可数名词的,加are/were
例句：
There are a few cakes left over from the party.
There are few of students in the classroom,they have went to the playground.