a sheet (of paper) 一张 a piece of a slice of bread 一片面包 一片拥挤 a crowd of a kind of a set of 一套;一组;一副 a suit of 一套 a group of 一组,一群 a sum of money a bunch of 一群;一束;一堆
a sort of 一种 almost same as a kind of a cup of 一杯 a mount of /amount of 一些(较大量) a pile of 一堆 piles of a pair of 一对(双)pairs of a pill of 一片 a gallon of ...
a couple of(两个、一对)—a couple of days,a couple of players,a couple of times a cupful of(一满杯)—a cupful of jelly,a cupful of water a portion of(一份/客)—a portion of duck,a portion of roast beef