求解“高难度”新概念三题目：they usually wear a collar and tie_____

求解“高难度”新概念三题目：they usually wear a collar and tie_____
they usually wear a collar and tie_____
A.as they work
B.to work
C.going to work
D.in order to work
这道题的正确答案是B,说是省略了to go
但是我想问问为什么不能选A 把它作为时间状语从句：当他们工作的时候,他们常常穿有领子的衣服,系领带?
或是选D .翻成：为了工作,他们常常穿有领子的衣服,系领带?
另：my promotion brings into question the status of certain other members of staff 句子结构是怎样的？