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：考查情景交际和时态。句意：--有什么问题吗，鲍勃？你看起来不开心。--噢，没什么。事实上，我（刚才）正在想家里的朋友们。根据情境可知，鲍勃刚才一直在想他的朋友，现在鲍勃的思考被打断了。过去正在进行的动作，用过去进行时。故选B。
