---I usually have an egg and some bread for breakfast A.so do I B.so have I C.so I d

问题补充：

---I usually have an egg and some bread for breakfast.

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A.so do I B.so have I C.so I do

答案：

解析：肯定形式的倒装句用：so+助动词+主语， have为实意动词“有”，故应用助动词do。所以选A。