—I didn't go to see the doctor yesterday.
—But you .
A. ought
B. ought to
C. oughted to
D. ought to have
网友回答
A. ought
B. ought to
C. oughted to
(答案→)D. ought to have
解析：从对话中可以看得出来,双方谈论的话题是过去的事,故应用ought to have +过去分词,省略时,则须在to之前加上have。错选B者主要是没注意到句中的yesterday,是表过去,而非现在。