.keep好既是实义动词同是又是系动词,作为实义动词,它是一个及物动词,这时它后面接宾语,作为系动词它后面接形容词作表语.

eg:We must keep our classroom clean.(这句中的keep是及物动词)

常见的系动词还有look,feel,taste,smell,get,go,come,become,

turn,grow.

eg:Child though he is ,he knows a lot.这是一个高中语法,你以后就会学到.

3.crowded不是不及物动词而是形容词,它的动词形式是crowd它既是一个及物动词,又是一个不及物动词,

eg:He crowded more books onto the shelf.