在他表弟家用英语怎么说

在他表弟家用英语可以说成 "at his cousin's house" 或者 "at his cousin's place."
"Cousin" 在英语中指的是 "first cousin"，也就是父母的兄弟姐妹的子女。"Cousin" 这个词来源于拉丁文 "cognatus"，意思是 "having a common ancestor."
下面是一些例句：
"I'm going to my cousin's house for Thanksgiving dinner." (我要去我表弟家吃感恩节晚餐。)
"I'm staying at my cousin's place for the weekend." (我呆在我表弟家过周末。)
"I'm visiting my cousin and his family at their house." (我正在拜访我表弟和他的家人在他们家里。)