a few of是单数还是复数

问题描述:

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……

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.