I was quite surprised when I read in your letter that you had decided not to finish your studies at the university.
当我在你的信中看到你已决定终止大学学业时感到很是惊讶。
and you avoid the frustration of arriving at the very moment when the train is drawing out of the station and being unable to get on it.
而且可以避免那种正好在火车驶出站时赶到车站,因上不去车而感到的沮丧。