2. 当整个从句被省略时，可用so来代替。这样的主句谓语动词有：think, believe, guess, suppose, hope, be及疑问副词why, how, if等。如：

(1) —Do you think the thief will be put into prison? 你认为那个贼会被打入监牢吗？

—Yes. I think so. 是的，我认为会。

(2) —Do you believe that he will come back from abroad? 你认为他会从国外回来吗？

—Yes. I believe so. 是的，我认为他会回来。

(3) —It is said that Mary got her arm broken. 据说玛丽把手臂弄断了。

—How so. 怎么会这样呢。

(4) —He must be in the classroom now. 他现在肯定在教室里。

—If so, let’s go to the classroom to see him. 如果她在教室里，我们就去那儿看他吧。

3. 当从句为否定，而整个从句被省略时，可写为don’t…so, 也可只保留从句中的not。这样的主句动词有：think, believe, suppose等。如：(www.hxen.com)

(1) —Do you think he will change his idea? 你认为他会改变主意吗？

—No. I don’t think so. 不，我认为他不会。

(2) —Do you think English is difficult? 你认为英语难学吗？

—No. I don’t think so. 不，我认为不难学。

四、从句中的引导词省略后，主谓倒装

在虚拟条件句中含有were, should, had 时，可将 if 省略，同时将 were, should, had 提到句首。如：

(1) Were I there, I would stop him doing that. 要是我在那儿，我就会阻止他那样做。

(2) Had he learnt English, he would be studying abroad. 要是他以前学过英语，他会正在国外学习。

(3) Should he like swimming, I couldn’t stop him. 要是他喜欢游泳，我可阻止他不了。