句子成份repaymentofwhichhemaydemandatanytime

When anyone opens a current account at a bank, he is lending the bank money, repayment of which he may demand at any time

repayment of which是定语从句的引导词，which指代的是money。
定语从句还原后为：
Repayment of (the money = which) may demand at any time. 该钱款的偿付可以随时索要。

这种用法并不罕见，当指代的词在从句中做定语时，就写成这种格式。而这是可以和whose互换的：
,he is lending the bank money, repayment of which he may demand at any time.
= ,he is lending the bank money, whose repayment he may demand at any time.

例如：
Look at the building, the roof of which is
white.
=Look at the building, whose roof is white.

你好！ money的同位语 仅代表个人观点，不喜勿喷，谢谢。