当数量概念作主语时主语一致的用法

1. 表时间长度、钱数、速度等的词组作主语时，通常将其视为整体，谓语动词用单数。如：

Twenty years is a long time. 20年是很长的时间。

Ten dollars is all I have left. 我只剩下10美元。

2. “分数(百分数)+of+名词”结构作主语时，谓语动词的数与其中名词的数保持一致。如：

About 20 percent of the pupils were absent that day. 那天大约有20%的学生未到。

Three-fourths of the surface of the earth is covered by sea. 地球表面的四分之三是海。

注：在现代英语中，有时即使该结构中的名词为复数，其谓语也可用单数(即将其视为整体)。如：

Over eighty per cent of families own [owns] a television. 百分之八十以上的家庭已拥有电视机。

3.“one in [out of]+复数名词”作主语时，谓语动词通常用单数。如：

Only one in ten students has passed the examination. 只有十分之一的学生通过了考试。

One out of twelve bottles was broken. 每12个瓶子中有一个破了。

注：在非正式文体中有时也用复数谓语。如：

Nationwide, one in five adults are illiterate. 就全国范围而言，五个成年人中有一个是文盲。

4. “all of (some of, none of, half of, most of, lots of, plenty of)+名词”作主语时，谓语动词的数与其中名词的数保持一致。如：

Half of the apple is bad. 这个苹果有一半是坏的。

Half of the apples are bad. 这些苹果当中有一半是坏的。

Half of our money goes on food. 我们有一半的钱花在食物上。

5.“one and a half＋复数名词”与“a＋单数名词＋and a half”作主语时，国内不少书认为，这两个结构作主语，谓语均用单数。如：

One and a half months has passed. / A month and a half has passed. 已经过去了一个半月。

但是，国外一些词书则认为，谓语动词的数取决于这两个结构中名词的数。如：

One and a half months have passed. / A month and a half has passed. 已经过去了一个半月。

6.“the [a] number of+名词”作主语时，该结构若用定冠词，其后谓语用单数；若用不定冠词，其后谓语用复数。如：

The number of people invited was fifty, but a number of them were absent for different reasons. 有50人被邀请参加，但是很多人因为各种原因而缺席。