plastic本身是个不可数名词,但是加上s后表示各种各样的塑料材质.
和它用法一致的还有vegetable,food,fruit等,加上s后表示各种各样的蔬菜水果或者食物.
These spoons are made of plastic.(不可数)
这些汤匙是塑料制的.
Plastics are used in many modern articles instead of metal,wood,etc.(可数)
塑料在许多现代用品中被用来代替金属、木材等.
Nowadays we can use plastic instead of cash in many places buying things..(可数)
如今在许多场所都可以用信用卡代替现金来购买物品.