—Tom, how forgetful you are! I found you left your key in the keyhole this morning.
—Oh, dear! .
A. So had I
B. So I had
C. So did I
D. So I did
网友回答
A. So had I
B. So I had
C. So did I
(答案→)D. So I did
解析： 句意：--汤姆，你多么健忘啊！我发现你今天早上把钥匙拉在钥匙孔里了。--哦，天哪，确实是。So+主语+助动词/be动词/情态动词，表示“是的”，因为上文是I found you left your key in the keyhole this morning.所以助动词用did，所以选D。