3.由do，so等组成的复合替代形式

(1)so+助动词+主语。

—Mary will enter the university in September．—So will Joan．

——玛丽将于九月上学——琼也是。

(2)so+主语+助动词。

—I've been to Beijing．—So you have．

——我去过北京。——是的。

提示：

这种结构中第二句的主语与第一句的主语是同一个人，否则应像“so+助动词+主语”的结构一样，主谓要倒装。

(3)主语+do+so。

—Have you sent your plan to the committee?—I did so yesterday．

——你把你的计划递交给了委员会吗?——我昨天就送去了。

If you need to buy foreign currency，it is usually cheaper to do so in your home country．(人教大纲版高二下第39页)

如果你要买外币，那么在国内兑换通常会便宜些。

After dinner my uncle said he wanted to sleep，and it seemed as if he really did so．(人教大纲版高二上第76页)

饭后叔叔说他想睡觉，仿佛他真的想睡觉。

(4)主语+do+that。

—Do you know who broke the television set?—I heard John did that．

——你知道是谁把电视砸坏的吗?——听说是约翰砸的。

(5)主语+(助动词+)do+it。

My brother said he was going to send a letter of protest to the President，and I did it last week．

我弟弟说他想寄给总统一封抗议信，我上个星期已经做了。

提示：

如果上文表示否定意义而在简短反应中表示相同的看法时，则用“neither/nor+do+主语”。此时，do不是动词替代词，而是助动词。

Mary didn't like English，neither did her brother．

玛丽不喜欢英语，她弟弟也不喜欢。