有这样一道题：

Mrs Brown was much disappointed to see the washing machine she had had _________ went wrong again.

A. it B. it repaired C. repaired D. to be repaired

这是一道上海高考英语题，答案选C，许多考生因不能正确分析句子结构，不知如何下笔。现分析如下：句中to see 后的基本结构是：the washing machine went wrong again.(洗衣机又出毛病了)，其中 (that) she had had repaired 套用的句型是“have + 名词或代词 + 过去分词”，即 have the washing machine repaired;另外，从时间上看，“请人修洗衣机”应在“出故障”之前，故 have the washing machine repaired 用了过去完成时态，即用 had had the washing machine repaired;从修饰角度看，题目中she had had repaired 为修饰名词 the washing machine 的定语从句(意为“她曾请人修理过的洗衣机”)，引导该定语从句的关系代词为 that，因其用作宾语被省略，也正因为如此，题目中的 she had had repaired 的第二个had 后既不能用 the washing machine 或 it，这也就是为什么不能选B的原因。如果有的同学还明白，我们可以从反面来分析一下：假若选B，则有 (that) she had had it repaired，而它作为修饰 the washing machine 的定语从句是有问题的，为什么有问题呢?那是因为 she had had it repaired 这个句子的结构(或成分)是完整的，它有主语、有谓语、有宾语，这样一来，引导这个定语从句的关系代词 that 就没有着落了，因为关系代词 that 要么作主语(不可省略)，要么作宾语(可以省略)，而 she had had it repaired 这个定语从句既不缺主语，也不缺宾语，所以错了。假若去掉其中的 it，即改选C，则对了，因为这样一来，that 可用作动词 repaired 的宾语。现在我们将此题改编一下，将其改为：

Mrs Brown was much disappointed to see the washing machine she had _________ went wrong again.

A. it B. it repaired C. repaired D. to be repaired

答案应选哪个呢?选B还是C?仍然要选C，但是意思变了，即“她自己修理过的洗衣机又出故障了”，因为此时修饰 the washing machine 的定语从句变成了 she had repaired。不能选B，道理同上。

请比较下面一题：

A computer does only what thinking people _________.

A. have it do B. have it done C. have done it D. having it done

答案选A，选项中的 it 指的是 the computer，而不是指 the work 之类的。其中的 what 用作动词 do 的宾语。句意为“人们要计算机做什么，它就做什么”。