http://www.pkuschool.com/teacher/details.asp?TopicAbb=design&SubjectAbb=yy&FileName=g1v4yy65020a03.htm&FileID=55489&Title=the%20silver%20screen
这个是北大附中的网教页面
上面有写
Teaching Aids:
1. a VCD
2. a TV set
3. a tape recorder
4. a projector
我想问有没有人知道其中 Teaching Aids 是什么意思