vegetable 蔬菜的总类，泛指蔬菜。vegetable那一类,就是总称。+s后就是实际的是那些蔬菜，具体的。
表示蔬菜的种类
当用于表示蔬菜的种类时，为可数名词。
e.g. There are two vegetables in my vegetable garden；
表示蔬菜这一整体概念
当用于表示蔬菜这一整体概念时，则为不可数名词。
e.g. We should often eat vegetable which is good for us.
拓展资料
The freshmen always seem like vegetables.
新生看起来总像植物人。
Since the car accident, she's just been a vegetable.
自从那场车祸以来，她一直是个植物人。
Since she suffered brain damage in the accident she's been a vegetable.
自从事故中脑子受损坏后，她成了植物人。
The tomato is technically a fruit,although it is eaten as a vegetable.严格地说，西红柿是一种水果，尽管它是当作蔬菜吃的。
