贾宝玉初试云雨情:what is system ?

what is system modelling what is system ? Describe what a Global distribution system (GDS) is what system of the human body is made up of blood,blood vessels or the heart what system of the body is made of the brain,the spinalcord,and the nerves what is done is done what is oicq? What is WINS？ What is 对冲基金? What is photoshop?