复数： backpacks

I sat down at a table and opened my backpack .

我坐在一张桌子旁，打开我的背包。

I will keep it in my backpack .

我将会把它装在背包中。

I will bring them in my backpack .

我会把它们装在我的背包里。

Her backpack was the same colour !

她的背包也是同样的颜色！

It looks like a model aircraft . When disassembled it fits into a backpack .

它看上去就像模型飞机，拆卸以后正好可以放进军用背包。