It's my backpack.对my backpack提问X详细点都写出来

我的棒球 意思

这是我的背包
backpack：A knapsack, often mounted on a lightweight frame, that is worn on a person's back, as to carry camping supplies.
背包：一种背在背上的通常安装在轻量结构上的背包，用来带一些野营的必需品
A piece of equipment, often containing life-support devices, designed to be used while being carried on the back:
背伏的东西：设计成背在背上使用的一种装备，通常包括生活供应设备：
a parachute in a backpack; an astronaut's backpack.
背伏降落伞包；宇航员背包