一只手臂英文怎么说

一只手臂英语可以说成 "an arm"。

"Arm" 这个词来源于古英语 "ærm"，意思是人体上连接手和身体的部分。它最早的记录可以追溯到十七世纪。

例句：

He broke his arm while playing football. (他在踢足球时手臂骨折了。)
She has a scar on her arm from a burn. (她的手臂上有一个烧伤的伤疤。)
He hugged her with both arms. (他用双臂拥抱她。)