beside oneself 请问这个是什麼词性?

Question

是副词还是形容词?
我意思是说 在整句话里面的词性
They were beside themselves in joy.

Answer 1

beside oneself 极度兴奋；发狂

从以下例句可见,是副词性的.

So, not necessary to how does a time bomb go up beside oneself.
所以，没必要给自己身边安上一粒定时炸弹。
Oppressor lets Huo Jia sit beside oneself, say gently to his ear: "Is you married still celibate?"
暴君让霍加坐在自己身边，对着他的耳朵轻轻地说：“你结了婚还是独身？”
A reader related a story that produces beside oneself in the incoming letter: Two campus lover lived together near one year.
一位读者在来信中讲述了一个发生在自己身边的故事：两名校园恋人同居了将近一年。

又可用于这个句型.
be beside oneself 极度兴奋，对自己的感情失去控制; 忘乎所以; 极度兴奋，对自己的情感失去控制; 极度兴奋,对自己的感情失去控制;

可见,两用的.

Answer 2

besides这里是介词

Answer 3

形容词性短语，were是系动词，系动词后面要加形容词

Answer 4

介词短语做表语来的。