So + do (be, have, can, will) + 主语：表示同样肯定的看法或做法。

（1）neither / nor + do (be, have, can, still) + 主语

表示同样否定的看法或做法。

You are not a doctor. Nor is he.

（2）so it is / was with sb. = it is / was the same with sb.

用于既有肯定又有否定或既有系动词又有实义动词的情况。

John likes fish but he doesn’t like meat, so it is with Mary.

（3）so + 主语 + do(be, have, can, will)

表示对前文提及的情况给予肯定

Tom speaks English well, ans so he does.

（4）主语 + do(be, have, can, will) + so

表示该句中的主语重复了前文中的动作。

The teacher asked me to fetch some chalk, and I did so.