.—May I remind you that a Mr. Zhang is waiting downstairs sir? —Oh dear. I about it.A.

问题补充：

.

—May I remind you that a Mr. Zhang is waiting downstairs, sir?

—Oh, dear. I about it.

A. forget

B. forgot

C. have forgotten

D. had forgotten

答案：

A. forget

(答案→)B. forgot

C. have forgotten

D. had forgotten

解析：考查时态。“先生，一位姓张的先生在楼下等你。”“噢，天啊！我忘记了。”指对话之前的事情，应该用一般过去时，即刚才忘记了。故选B。