34 --I can't find Mr Smith. Where did you meet him just now?

where (表地点）

补答：

既然，您对答案不满意。让我详细讲解。以前给学生讲课，强调的是语感，多给学生练类似的经典口语，台词之类。今天破例，I will give u a more detailed answer.

首先（_____ he worked）是一个定语从句修饰前面的office,说明是什么样的office, 是他工作的office. office 又回答了前句的where(Where did you meet him just now). 显然，用where引导一个定语从句，而且where的先行词是office.

其次，选B，C或D的话，它们(which, that, the one)在从句中都是work的宾语（A, WHERE不是，where是做状语）。而在英语当中work 表示工作（动词）的时候，是不及物动词，是不能有宾语的。
work要接上宾语,做及物动词，就是使工作的意思（而不是工作，是使别人或东西工作）。
如：
To cause to work:
使工作：
works his laborers hard.
让他的工人努力工作

如果选了Which， that或the one, 给native speaker的感觉就是：他让他的办公室工作了。而这是不合逻辑的。

举例：It was the disco where she found her boyfriend.
It was China where the couple adopted a child.
It was Shanghai where he worked.

I can't find Mr Smith. Where did you meet him just now?
--It was in his office _____ he worked.
A. where B. which C. that D. the one

of course choose A
句子强调的是地点