hug sb in one's arm正確嗎

不對，應該是hug sb by the arm，因為這是一個固定搭配，動詞+介詞+the +人體部位。中文意思是，擁抱某人的手臂

同類例句

The officer grabbed him by the arm.

警察抓住了他的手臂。

He seized her by the arm.

他抓住她的胳膊。

She was led by the arm to a small room at the far end of the corridor

她被拉著胳膊帶到走廊另一頭的一個小房間裡。