I was ____the point of telephoning him when his letter arrived

问题描述:

I was ____the point of telephoning him when his letter arrived
A:to
B:on
C:at
D:in
选哪个?为什么?

on
on the point of doing 正要做.
I was ____the point of telephoning him when his letter arrived.
我正要给他打电话,这时他的信到了.