问题补充：
—I’ve got to go now.
—Must you ?I you could stay for dinner with us.
A. think
B. thought
C. have thought
D. am thinking
答案：
A. think
(答案→)B. thought
C. have thought
D. am thinking
解析：考查动词时态。从对话语境可以看出对方要走，我想对方可能和我们一起吃饭应该发生在现在的以前，所以是现在和过去的对比，选B符合。
