gǔ / wén / zhōng / xiě / dào / xiān / sheng / xià / táng / hòu / xué / sheng / men / réng / liú / zài / táng / zhōng

古文中写道，先生下堂后，学生们仍留在堂中。

The classical text says that after the teacher left the hall, the students remained inside.