1.somebody是不定代词,多用在肯定句中,指未知或没有明言的某人,用作主语时谓语动词用单数形式,其相应的代词一般用he, himself或his,在非正式用语中也可用they, themselves或their。
2.在反意疑问句中,当陈述部分的主语是somebody时,在非正式语体中附加疑问句的主语往往用they。

That must be somebody from the Ministry of Education.那一定是教育部里的人。
Somebody has parked his car right in front of mine.有人将车子正好停在我的车子前面。
Somebody tried to gatecrash, didn't they?有人想无票入场,是不是?

somebody, one, someone
这三个词都可指“某人”。
1.somebody多用于口语; someone多用于书面语。
2.someone不可跟of短语; one可跟of短语。

somebody也可用作名词,意为“重要人物”。例如:
He thinks he is somebody in his own village.他认为自己在村上是一个有影响的人物。