it is clean when it is black.it is dirty when itis white.what is it
问题描述:
it is clean when it is black.it is dirty when itis white.what is it
答
黑板
答
blackboard黑板
答
干净的时候是黑的,脏的时候是白的,这是什么东西呢?
黑板Blackboard
答
黑板
Black board