有一读者问： 有一道选择题：
(1)There could no longer be any doubt that they were robbers. He counted forty_________them.
A. among B. from C. to D. of
答案是D，为什么？
这里应选D，不论介词of表同位关系或是表部分关系。如表同位关系，forty of them即意味着“一共有40个强盗”。这种表同位关系的of在英语中不乏其例，再如：
(2)There are three of us. 我们一共有三个人。
(3)We are only three poor men of us.
数词之前也常用定冠词the，如：
(4)He had ordered dinner for the two of them. （亦可说the pair of them）
(5)The three of them had risen to their feet together. （亦可说all the three of them或all three of them）
顺便提一下，下面词句中的of亦表同位关系。
(6)All of the defendants were proved guilty.
(7)He got angry with both of us.
(8)It was a slip of a girl.
(9)the City of Rome
(10)the kingdom of Denmark
在一定的上下文中，上述句（1）中的of也可能表部分关系。这样，forty of them即意味着“他们中的40个”。甚至还有可能意味着“看不太清楚，至少有40个”。
