问题补充:
—I studied in the United States for 3 years.
—.
A. So I did.
B. So was I.
C. So did I.
D. So do I.
答案:
A. So I did.
B. So was I.
(答案→)C. So did I.
D. So do I.
解析:考查倒装句:句意:--我在美国学习了三年。--我也是。So+be动词/情态动词/助动词+主语,意思是“某人也是”,因为第一句话是实意动词studied,所以答语是助动词did,选C。