单位词的使用
不可数名词表示多少，一般用much,little,a lot of,enough 等词表达，要数1，2，3，4时要用量词表达，最常用的是a piece of。
成双成对的名词一般用复数，如：a pair of trousers/ scissors/ glasses/ pliers
a couple of表示一对，或2-3，如：a couple of days / people / things
记住以下量词表达方式：
a loafof bread面包)
a burst of laughter
a fit of anger / chill
a game of chess
a lump of sugar
10、其他应注意的数的表达形式
1)a three-year-old boy 比较The boy is three years old
2)five thousand people / several thousand people比较 thousands of people
表达具体数字时，thousand不加 s，后面不加 of ; ten,million,billion情况以此类推。
3)One-third of the students have passed College English Test Band IV.
Two-thirds of the students have passed College English Test Band IV.
One-third of the population in this area is living below the poverty line.
注意：几分之几的表达形式;动词的单复数由后面的名词数决定。
4)a looker-on 比较two lookers-on/ a brother-in-law比较two brothers-in-law
5)my father,together with结构中，主语作单数处理，即my father.