教室里有三串钥匙用英语怎么说

"In the classroom, there are three strings of keys."
"Strings of keys" 是用来描述多个钥匙串的短语。"String" 在这里指的是一个绳状物，而 "of keys" 指的是用这个绳状物连接起来的钥匙。
例句：
"I always carry a string of keys with me so I don't lose them." (我总是随身携带一串钥匙，这样我就不会把它们丢失了。)
"She had a string of keys hanging from her belt." (她腰间挂着一串钥匙。)
"He took the string of keys and unlocked the door." (他拿起钥匙串并开了门。)