"是牛"是指一个人非常厉害或者优秀。在英语中，常用的表达方式包括：
"He/She is a genius." 这句话的意思是他/她是一个天才。
例句：
"Albert Einstein was a genius. He developed the theory of relativity." 阿尔伯特·爱因斯坦是一个天才。他发明了相对论。
"He/She is very talented." 这句话的意思是他/她非常有才华。
例句：
"My friend is a talented artist. She can draw and paint beautifully." 我的朋友是一个有才华的艺术家。她画画和涂鸦都非常漂亮。
"He/She is very skilled." 这句话的意思是他/她非常熟练。
例句：
"My brother is a skilled carpenter. He can make all kinds of furniture." 我的哥哥是一个熟练的木匠。他会做各种家具。
"He/She is a pro." 这句话的意思是他/她是个专业人士。
例句：
"My sister is a pro at playing the piano. She has been playing for years and has won many competitions." 我的姐姐是一个钢琴专业人士。她弹钢琴多年，并且赢得了很多比赛。
"He/She is a genius." 这句话的意思是他/她是一个天才。
例句：
"Albert Einstein was a genius. He developed the theory of relativity." 阿尔伯特·爱因斯坦是一个天才。他发明了相对论。
"He/She is very talented." 这句话的意思是他/她非常有才华。
例句：
"My friend is a talented artist. She can draw and paint beautifully." 我的朋友是一个有才华的艺术家。她画画和涂鸦都非常漂亮。
"He/She is very skilled." 这句话的意思是他/她非常熟练。
例句：
"My brother is a skilled carpenter. He can make all kinds of furniture." 我的哥哥是一个熟练的木匠。他会做各种家具。
"He/She is a pro." 这句话的意思是他/她是个专业人士。
例句：
"My sister is a pro at playing the piano. She has been playing for years and has won many competitions." 我的姐姐是一个钢琴专业人士。她弹钢琴多年，并且赢得了很多比赛。