have
1.have done it和have it done在语法结构上不同。have done it里的have是助动词，have done是完成时态，have it done里的have是使役动词，done是表语。have it done的完成时态式是have had it done。比较下面三句：
- I have cut my hair. （我已经剪了头发。）
- I have my hair cut every week. （我每星期使我的头发剪去。）
- I have had my hair cut. （我已经使我的头发剪去。）
在第二和第三句的译文里我都用“使”字。其实不一定有“使”的意思，假使说“我每星期被人剪去头发。”也可以说I have my hair cut every week。大概看了全句可以看出是否有“使”的意思，如I have had my pen mended有“使”的意思，I have had my pen stolen没有“使”的意思。当然并没有绝对的标准，假使说“我已经‘故意’使我的笔被人偷去”也可以说I have had my pen stolen。
下面第一句和第二句有“使”的意思，第三句和第四句没有：
- I should like to have my son taught English.
- He had a tooth pulled out yesterday.
- The house had one of the windows broken in the storm last week.
- The boy is sorry to have had his dog struck by a neighbour.
在have it done这种结构里，过去分词的动作者通常不是have的主语，如I have had my pen mended和I have had my pen stolen里的“修笔者”和“偷笔者”都不是I。
但把have it done的结构用在祈使语气里，那过去分词的动作者往往就是have的主语，如Have this pen mended可能是“叫人把这枝笔修一下”，也可能是“自己把这枝笔修一下”。
2.have后面接宾语和没有to的不定式有时有“使”的意思，有时没有。例如：
- I have him write to me every week. （我要他每星期写信给我。）
- I shall have him write to me every week. （我将要他每星期写信给我。）
- I will have him write to me every week. （我要使他每星期写信给我。）
第三句在美国比在英国流行，have him作“请他”或“吩咐他”解都可以。在英国说“请”通常用get，后面的不定式有to，如I will get him to write to me every week。说“吩咐”通常用make，后面的不定式没有to，如I will make him write to me every week。
是否有“使”的意思，并没有绝对的标准。“他弄死了她”也可以说He had her die。
下面第一句和第二句有“使”的意思，第三句和第四句没有：
- I will have someone to translate the story for me.
- I must have the boy clean out the drawers.
- I had an extraordinary thing happen to me when I was a little boy.
- We shall be sorry to have you leave us.
下面两句里的have作“允许”解：
- I won't have him write to me every week.
- I won't have you say such things.
3.比较下面三句：
- We shall soon have a young man work with us. （我们不久将有一个青年跟我们一道工作。）
- We shall soon have a young man to work with us. （我们不久将有一个跟我们一道工作的青年。）
- We shall soon have a young man working with us. （我们不久将有一个青年继续跟我们一道工作。）
实际上这三句的意思可以算没有区别。
下面两句意思相同：
- I would have you know that you must not make the mistake again.
- I would have you to know that you must not make the mistake again.
下面两句里的现在分词不可改作不定式，因为都有“正在进行”的含意。
- We shall soon have the mist rising.
- In a few minutes he had us all laughing again.
下面每组里的两句意思相同，但第二句比第一句生动：
- I can't have you do nothing all day.
I can't have you doing nothing all day. - I hope to have you all speak correct English within a year.
I hope to have you all speaking correct English within a year,
4.have往往用作“收到（信件）”或“已经收到（信件）”解，如I have had two letters from him recently和I have your letter。
5.I have something to say是“我有一些话要讲”。I have to say something是“我不得不讲一些话”。比较：
- I had something to say, but I had no chance to say it.
- I had to say something, but I could find nothing to say.
That is the only thing that I have to say可能有两个意思：“那是我能讲的唯一的话。”（that是have的宾语）或“那是我不得不讲的唯一的话。”（that是say的宾语）
但下面每组里的两句在意思上很少区别：
- Every one of us has his work to do.
Every one of us has to do his work. - I have four letters to reply to this morning.
I have to reply to four letters this morning.
6.比较下面各句：
- I should like to see him. （1.我将乐于见他。2.我很想见他。）
- I should like to have seen him. （1.我将乐于曾经见他。2.我巴不得曾经见他［实际不曾见他］。）
- I should have liked to see him. （1.我将曾经乐于见他。2.要是当时我见了他，当时我将感到快乐［可惜当时不曾见他］。）
- I should have liked to have seen him. （1.我将曾经乐于曾经见他。2.要是在当时以前我曾经见他，我在当时将感到快乐［可惜当时以前我不曾见他］。）
英美人往往在该用第三种形式的场合误用第四种形式，有时在该用第三种形式的场合误用第二种形式。
7.下面各句都可以说：
- He intended to come yesterday.
- He had intended to come yesterday.
- He intended to have come yesterday.
- He had intended to have come yesterday.
第一句没有“他实际不曾来”的意思，第二句往往有这意思，第三句和第四句总有这意思，第四句不算正当。把intended改作hoped, expected, meant, feared等词也是这样。
8.下面三句里的have...都表示“实际不曾…”的意思：
- We were to have met at five o'clock, but somehow I had to cancel the appointment at the last moment.
- He was clever enough to have answered all the questions.
- I was going to have knocked, when the door opened.
9.比较下面各句：
- He seems（或appears）to be interested in our work. （他［现在］好像关心我们的工作。）
- He seemed（或appeared）to be interested in our work. （他当时好像关心我们的工作。）
- He seems（或appears）to have been interested in our work. （他［现在］好像曾经关心我们的工作。）
- He seemed（或appeared）to have been interested in our work. （他当时好像在当时以前曾经关心我们的工作。）
英美人往往在该用第三种形式的场合误用第四种形式。
10.关于助动词do和have用在一起，参见do 9和10
