问题补充：
--- Beijing has improved a lot these years. ---- and .
A. So has it, so has Shanghai
B. So has it, so Shanghai has
C. So it has, so Shanghai has
D. So it has, so has Shanghai
答案：
A. So has it, so has Shanghai
B. So has it, so Shanghai has
C. So it has, so Shanghai has
(答案→)D. So it has, so has Shanghai
解析：句意：这些年北京改善很多。是的，上海也是。And前句子是在对前一人的说话内容肯定，该用so的半倒装句即so + 主语 + 系动词be或助动词；and后句子是说前者的情况也适合后者，该用so的全倒装句即so +系动词be或助动词 + 主语。所以选D。
