It was on a train I was travlling to Xi’an I made the acquaintance of the old professor

问题补充：

It was on a train I was travlling to Xi’an I made the acquaintance of the old professor from UK.

A. that; where

B. that; that

C. which; that

D. where; that

答案：

A. that; where

B. that; that

C. which; that

(答案→)D. where; that

解析：考查定语从句和强调句：句意：就是在我去西安旅行的火车上我认识了来自英国的老教授。第一空是定语从句，先行词是a train，定语从句中缺少地点状语，填where，相当于on which，第二空是强调句结构：It was+强调部分+that+其余部分。强调的是on a train，选D。