这个句子为什么要放个of？

of the following

你可以把这一句去掉 即：which is true .

这样好明白么？

因为是在following中择其一

对头
which of these is ture?

which is ture of (the following )/(these)?就是其中之一的意思， 变成these看看是不是不能不加of 阿

Sth of the following is ture.
如果没有of
sth the following is ture.你觉得对么？
sth 是名词 the following 也是名词。

of 是介词,表示在...范围之类