The young girl dressed in red is my daugher.

The young girl dressed in red is my daugher.
为什么用dressed,而不用dressing?
因为dress在这个时候,后面要加宾语,正常的用法是：
dress sb 给某人穿衣服.如果其后没有sb,也就是宾语,那dress就要用dressed,这一点一定要记住.
这句话可以这样理　the young girl (who was) dressed in red is my daughter.
同样的用法还有：seat,它当定语时,后面没有宾语时,也要用seated.
The man seated /sitting under the tree is his uncle.