1.3.7.2. it 与 which

请看以下两组句子：

1. Tom didn’t get married until thirty; it made his parents worried.

Tom didn’t get married until thirty, which made his parents worried.

2. Jim, the most hardworking student, didn’t pass the exam. It surprised us all.

Jim, the most hardworking student, didn’t pass the exam, which surprised us all.

显然，it(It) 连接两个独立或平行的句子;而 which 引导一定语从句。

1.3.7.3. as 与 which

仔细比较下列句子：

Mary was remarried, which/as was natural.

Mary was remarried, which made her parents less worried.

Linda was remarried, which was inglorious(不光彩).

Linda was remarried, as we had expected.

Mary was remarried, as we had expected.

As we had expected, Mary was remarried.

Don’t make such foolish mistakes as I’ve made.

Do you have the same dictionary as she has?

which 和 as 都可引导非限制性定语从句，替代上文中整个一句话的内容。

非限制性定语从句若是否定式，或从句含有消极意义，或从句是主谓宾(状/补)结构且缺主语等情况时，只能用 which。

若非限制性定语从句位于句首，或有“正如……，正像……，这一点”等意义，或先行词被 such，same 修饰时，那么替代词只能用 as。

7. 替代词 so

英语中，某些动词如 do，say，hear 或表看法的心理活动的动词 think，hope，believe，expect，suppose，guess，fear，be afraid 等以及特殊句型中，常用 so 替代上文中的内容或情况。

Who dared (to) say so then?

— The new teacher is very strict.

— I’ve heard so.

— Do you think we can get there in time?

— Yes, I think so. (No, I don’t think so.)

— Can you beat Class One?

— Yes, I believe so.

— Tom swims in the river every summer. — So do I.

— Tom swims in the river every summer. — So he does.

— Our teacher asked Tom to fetch some chalk. — He did so.

助动词

so +　 系动词 +主语 这一句型表示甲乙两个不同的对象具有相同的情况。

情态动词

助动词

so +主语+ 系动词　　这个句型表示甲陈述某一情况，听话人乙表示赞同甲的说法。

情态动词

助动词 主语+ 系动词 + so 　该句型是指甲吩咐、命令、叫乙去做某事，乙照办了之意义。