问题补充：
—Is there anything wrong, Bob? You look sad.
—Oh, nothing much. In fact, I of my friends back home.
A. have just thought
B. was just thinking
C. would just think
D. will just be thinking
答案：
A. have just thought
(答案→)B. was just thinking
C. would just think
D. will just be thinking
解析：
B。指刚刚在想念老家的朋友，故用过去进行时。
