I hear they’ve promoted Tom, but he didn’t mention _____ when we talked on the phone.
A. to promote B. having been promoted
C. having promoted D. to be promoted

B
I hear they’ve promoted Tom, but he didn’t mention _____ when we talked on the phone.
从句意判断，Tom已经升职，但说话者在与Tom打电话时，Tom并未提及自己升职的事。
升职发生在mention之前（不然就无所谓提及不提及），所以用have done形式，promote是及物动词，所以此处用be promoted。mention是及物动词，直接加宾语，不用不定式。
其实也就相当于He didn’t mention that he had been promoted when we talked on the phone.


mention
n.
提及, 说起
v.
论及, 提及
vt.
叙述, 说到, 讲到; 写到; 记载
提述:提名表扬
as mentioned above
如上所述
Did you mention this to my sister?
你对我姐姐说到这件事了吗?
The soldier was mentioned in a report for his bravery.
这个战士的勇敢行为被记载在报告书里。
Soon after going abroad with the army he was mentioned in despatches.
他随部队出国后不久便得到传令嘉奖。

参考文献：金山词霸