somebody表单数概念?例如everyone后谓语动词要接单数,但是为什么somebody后面的谓语动词有时接单数有

在英语上,我们把somebody anybody nobady something anything nothing someone anyone none 等等这样的词称之为复合不定代词,在不定代词之后,通常谓语动词用单三型式,（is was has).
复合不定代词在句子中作主语时,谓语动词一般用单数形式.如：Nobody knows his name.没有人知道他的名字.
陈述部分主语是不定代词everybody,anyone,somebody,nobody,no one等,疑问部分常用复数they,有时也用单数he.This is our new headmaster,isn’t it?
Those are Japanese,aren’t they?
One should be ready to help others,shouldn’t one?
One can’t be too careful,can you?
Each of the students has a dictionary,hasn’t he?
Each of the students passed the examination,didn’t they?
None of his money is left,is it?
None of his friends are interested,are they?
None of his friends has come,has he?
Something will have to be done about the price,won’t it?Everybody is kind to you,aren’t they?
No one left here yesterday,did they?
Someone turned that radio down,don’t they?
Neither side could win,could they?
Everything that he says is false,isn’t it?
I am older than you,aren’t I / ain’t
I am working now,ain’t I / am I not?
I wish to see the movie now,may
I wish I were you,may

somebody 翻译为某些人 或者 某类人