教室3b英语的翻译是"Classroom 3b"。
"Classroom"是英语中指"教室"的常用词，来源于拉丁文"classis"，意思是"分类、等级"。"3b"则是指教室的编号或名称。
下面是一些例句：
Please go to Classroom 3b for your Engpsh lesson. (请到教室3b上英语课。)
I have a class in Classroom 3b at 10 o'clock. (我10点有一节课在教室3b。)
Is Classroom 3b on the second floor or the third floor? (教室3b在二楼还是三楼？)