✔ 最佳答案
Virtual object is an object that is not exist and it is just an image. It may be an image produce by certain lens or mirror. With respect to another lens or mirror, it becomes an object. But as it does not really exist, it is called the virtual object.
2006-11-04 08:46:10 補充:
No matter it is an object or image, if it is virtual, use dotted line, if it is real, use continuous line.