A：磁带、磁盘、光盘等实体
B：文字、图形、图像、声音、动画、视频等载体
C：多媒体计算机、手机等设备
D：互联网、Photoshop、flash
试判断A、B、C、D各是什么物质：A____B____C____D____．
—The land in the southwest of China is in great need of .—Yes, it hasn't rained for a long time there.
声音通过头骨、颌骨也能传到听觉神经，引起听觉．这种传导方式叫做 ____．发出的声音遇到障碍物会被反射回来，根据回声到来的方位和时间，可以确定目标的位置和距离，这种方法叫做 ____
—Haven't seen you for ages! Do you still work in Xi'an?
—________. It's four years since I worked there.
