<例句>
I bought two bottles of ink yesterday.
我昨天买了两瓶墨水。
<语法分析>
单位名词的数有单、复数的形式，如kind, sort, type, piece, cake, bottle和grain等单位名词如与复数限定词连用，一般要变成复数形式，of 后面的名词多用单数形式，且不用冠词。有些单位名词如dozen, score, head等词语复数限定词连用，仍保留单数形式。但如表示一种不确定的复数时，用复数形式。有些单位名词如pair, couple和ton等于复数限定词连用时，可用单数也可用复数。this, that, another和every等单数限定词一般只能与单数名词连用，但复数名词前有一个集体数词，且被看作一个整体时，也可与this等单数限定词连用。
<触类旁通>
(1) I like that two kinds of apple.
我喜欢那两种苹果。
语法分析：单位名词如与复数限定词连用，一般要变成复数形式。
(2) The shop sells six kinds of hat.
这家商店出售六种帽子。
语法分析：of 后面的名词多用单数形式。
(3) I went to the students reading-room yesterday.
我昨天去学生阅览室了。
语法分析：名词有时也可用复数作定语。
(4) He is a seven-year-old boy.
他是个七岁的男孩。
语法分析：数词 + 名词作定语，这个名词一般保留单数形式。
(5) I go to see her every two weeks.
我每两周去看望她一次。
语法分析：复数名词前有一个集体数词，且被看作一个整体时，也可与单数限定词连用。
(6) Never make friends with such a person.
不要和这样的人交朋友。
语法分析：有些名词在某些习惯用法中，要用复数形式。
<巩固练习>
1. She eat twn _____[piece] of bread.
2. There are three _____[grain] of rice on the table.
3. There are two _____[score] of birds in the forest.
4. She bought three _____[dozen] of balls last week.
5. I have been there _____[dozen] of times.
6. Wealth was calculated by _____[head] of cattle.
7. The old man is a _____[shoe] doctors there.
8. I saw two _____[man] doctors there.
9. She came up to shake _____[hand] with me.
10. He asked me to change _____[seat].
<参考答案>
1. pieces 2. grains 3. score 4. dozen 5. dozens 6. heads 7. shoe 8. men 9. hands 10. seats
