When I got home last night I was frightened to find that in front of my door.A. sit a dog

问题补充：

When I got home last night, I was frightened to find that in front of my door.

A. sit a dog

B. sat a dog

C. was a dog seated

D. did a dog sit

答案：

A. sit a dog

(答案→)B. sat a dog

C. was a dog seated

D. did a dog sit

解析：考查倒装句。本题中把表示地点的介词短语in front of my door放在了句首，后面的主语是名词，故使用全部倒装的形式；句意：当我昨天晚上到家的时候，我很惊讶第发现在门前面坐着一条狗。故B正确。