blackboards的例句（blackboards在句子中的用法）

• Some cleaned the blackboards, others mopped the floor. 有些人擦黑板, 有些人拖地板.
• How many blackboards are there in this room? 在这个房间里有几块黑板?
• New blackboards have been fitted up in all the classrooms. 教室里都安装上了新黑板.