擦黑板

• Offer to stay after school to help clean blackboards , shelve15 books , or help straighten up16 the room , if you have time
  放学后如果有时间，主动留下来帮老师擦黑板，把书放回书架，或打扫教室。
• The students are cleaning the classroom . some are cleaning the blackboard ； some are sweeping the floor ； the other students are cleaning the window
  学生们在打扫教室。一些在擦黑板，一些在擦地板，另外的都在擦窗户。