and的单复数问题？

Question

1. a year and a half (has) elapsed.
2. two kilos and a half (have) sold out.

请问例1也大于1，例2也大于1，为什么一个用单数形式，一个用复数形式

Answer 1

其实跟and没关系的。

A year and a half (has) elapsed.时间主语，单数。（一年半）

Two years is not a long time.

Two kilos and a half (have) sold out.

2.5千克

时间、距离、度量、重量、金额等的复数名词作主语,被看作整体时,谓语动词用单数。个体时用复数。

Two kilos is heavy.


Ten dollars is too much for the book.这本书十美元太贵了。

Ten dollars were paid for the book. 这本书付了十美元。

Answer 2

a year and a half的谓语动词用单数，因为 year and a half被看作是一个时间段(a period of a year and a half)。
如果是one and a half years 则谓语动词常常用复数。