无意中看到本论坛上曹老师的一篇文章“比较分句than what中的what应该保留还是删去”（https://www.cpsenglish.com/article/219），他是借用Huddleston的“剑桥英语语法（2002）”来解释的，我也忍不住想说说这个话题，我尽量用很浅显的语言来描述。

任何一个比较句一般都能拆成两个独立的句子，拆好后的这两句再合在一起就可以变回原先的比较句，只是有2点要注意：一是比较要素（comparative element）在比较分句中必须删除（这是比较句的核心之所在），名词性的主语或宾语换为代词；二是还要注意比较分句的省略问题。

举例子说明：

1.You have more books than I (have).正确的标准英语，拆句如下：

You have some books.和 I have some books.

再合并：You have more books than I (have).

注意看后面一句的some books在合并后删除了，因为它是比较要素。其他的都可以保留，只是会显得整个句子没那么简洁，于是have可以省略（不省略也行）。

2. She has more books than me.那这一句是怎么回事？

它的根源在于它是这样理解的：

She has more than 50 books.（50只是举个例子）和I have 50 books.

可以写成这样：She has more books than me.

这里的than理解为介词，后面接宾语，所以用me。

其实than what的错误根源也在于此：

还是上面的例句：

She has more than 50 books.和I have 50 books.有人说这两句也可以合并成：

She has more books than what I have.（错句）

上面的分析似乎合理，其实是错误的，只是She has more books than me.由于使用非常广泛，所以被接受是正确的，而She has more books than what I have.不能被接受，可被认为是非标准英语（在极不正式的场合还是会有人这么用）

在这本“The Cambridge Guide to English Usage2004”的书中P534：

The most extended use of than as a preposition is to be seen in nonstandard usage such as:

He wanted it more than what I did.（非标准英语）

Such constructions provide an empty object for than but ensure the use of the subject pronoun in the following clause. It could thus be seen as a kind of hypercorrective response to the grammatical“problem” (see hypercorrection). The what is unnecessary because the sentence could perfectly well be:

就是把than的介词用法给放大了，或者说是推广了，这样是不对的！

He wanted it more than I did (or more than me)这一句本来就是正确的，加个what进去实际上是矫枉过正了。

举一些what要删除的例子：

I speak better English than what those foreigners do. (非标准英语)

Fruit is cheaper this season than what it was last year. (非标准英语)

He looks much happier than what he did yesterday. (非标准英语)

The damage was slighter than what I’d expected. (非标准英语)

注意区别这句：

The damage was different from what I’d expected.正确的，from是介词，有what才对

这些非标准的例句的特点很明显，比较要素是作表语的形容词比较级，比较的对象是主语，前面说了，比较要素在后面的比较分句中一定要删除的，这样看的话不用what整个句子就是成立的，不需要加what，这是多此一举。

章振邦的名著“新编高级英语语法（2012）”P674页有这么一句：

This meat is better than we had last week.（？？有问题）

拆句：This meat is good.和The meat we had  was good last week.

前面说了，合为一句要删除比较要素，变为：

This meat is better than that meat we had （was）last week .

这就是原句完整的样子。that meat是比较的对象，不要省略，而括号的was可以省略也可以不省略。

所以也可以改写成：This meat is better than what we had last week.

所以what要加进去，不能没有。

以下例句的what不能去掉：

The Internet service is better than what we bargained for.

The work you did today is much better/worse than what you did last week.

Mr McGregor's remarks are far worse than what Edwina Currie said about eggs.

This food is so much better than what they usually get.

What is new is not necessarily better than what is old.

She apparently liked it more than what we gave her.

大家可以按照拆句再合并的方法来验证一下what是要还是不要！

再举一个代表性的例子：

3. The matter was more serious than we had expected.（正确的句子）

照旧，拆，有两种拆法（这是由expect的用法决定的）：

[a] The matter was serious.和 we had expected that the matter would be serious.

[b]The matter was serious.和we had expected the matter to be serious.

合并的时候要删除比较要素即serious，后一句的the matter改为代词it(有两种写法)：

The matter was more serious than we had expected（that it would be）.

The matter was more serious than we had expected（it to be）.

这两句都是原句3的完整形式，只是省略了括号里面的而已（省略后的两句形式上完全一样了）。这里面需要what吗？不需要，因为已经是正确的。

顺便谈一下论坛上网友问的一个问题，在本论坛的“奶嘴CC”网友提出了这样一个问题（https://www.cpsenglish.com/question/48589）：

4. The economic situation is as serious as was expected.

上面这句是否是正确的？

照旧，as结构也一样，拆：

The economic situation is serious.和 The economic situation was expected to be serious.

再合为一句，去掉比较要素，名词主语换为代词it：

5.The economic situation is as serious as it was expected to be.

这一句句5就是句4的完整形式。接下来就看省略的问题，如何省略是另一个复杂的问题，我只给出我的理解：

句5可以同时省略it was和to be，变为句6：

6.The economic situation is as serious as expected.（as expeced是个习语）

能不能省略成句4的样子，即省略it和to be？我只能说这样做并不错，只是见到的少，不自然。但是以下句7的写法我认为是有问题的：

7.The economic situation is as serious as it was expected.（？）

不能只省略to be，要么都不省略如句5，要么it was和to be一起省略如句6。可以参考Quirk名著“ A Comprehensive Grammar of the English Language（1985年）”P1131。

章振邦的名著“新编高级英语语法（2012）”还是P674页也有这么类似的一句：

Progress with the building of the bridge was not so good as was expected.

同样，不能算错，只是不自然罢了！

这个句子章振邦的解释是：比较分句可以说省略了主语，也可以说是由as充当比较分句的主语，我对这个解释持保留意见。如果是说“省略了主语”，而没省略之前应该是as it was expected to be（as作表语，to be不能省略，这才对）。如果是说“由as充当比较分句的主语”，那as引导的限制性定语从句的先行词是什么？说不通嘛，这个说法很怪。我之所以这样质疑是因为这里面涉及到将as/than理解成关系代词充当主语，宾语或表语的用法，属于传统语法，关于这个问题争议很大，支持反对的都有。其实Quirk1985年在其名著“ A Comprehensive Grammar of the English Language（1985年）”中只用一句话指出（见P1131）：as/than的某些语法结构很像关系代词（然而在他1972年的那本A Grammar of contemporary English中却没有提这种说法，说明从1972-1985这十几年中他的水平仍在不断提高），注意他说是很像，没有说就是，而Swan也是认为很像，但都没有顺着这个思路展开讨论，而国内的语法几乎就把as/than直接当成关系代词来看待并深入研究了，在此我不作细评，很有意思的问题，有时间再聊。