【题目】---Your grandfather still seems very energetic, although he is already in his seventies now.
---Yes, he _______in the army for three years when he was young.
A． would serve B． served
C． had served D． has served
在线课程【答案】B
【解析】考查时态。根据第一句可知，“我爷爷”已经七十多岁了，第二句说的是他年轻时候在部队里待过三年，由此可知，在部队里是过去的事情，用一般过去时，故选B。