综述如下:1、crowding:可以作为动名词及进行时动词之用。2、crowded:作为形容词或过去分词。重点词汇:crowding英['kraʊdɪŋ]释义:n.拥挤,聚集;加浓短语:crowding out effect 挤出效应;排挤效应;排挤效果;效应。例句用作名词(n.)1、Year-round programs can also reduce crowding in schools.整年计划也可以降低学校拥挤的情况。2、More and more TV and radio stations are crowding the airwaves.愈来愈多的电视台和广播电台使无线电波段愈来愈拥挤。