do

英语的助动词 do 有一个很主要的用法: 在肯定句中表示强调。应注意, 在这种用法下它只有现在时(do, does)和过去时(did)。这种用法叫做强调肯定式(emphatic positive), 其作用在于排除否定性的观点:

1. So you did come after all. (Dreiser) 你毕竟还是来了。

2. But I do think you are a good cook. (CGEL) 但是,我确实认为你是个好厨师。(暗含的意思:你可能以为我并不这样认为。)

大家知道,do 用在动词之前,可起加强语气的作用:

Drive carefully! —— I do drive carefully. (LEG) 小心点开车！——我是很小心的。

do 用在祈使句中,能使请求显得更加客气而友好,或者更具有鼓励作用:

1. Do have another cup of tea. (LEG) 请再喝杯茶吧。

2. Do wait a moment! (LEG) 请等一会!

当然,在表示制止某种行动的祈使句中,加上助动词 do, 可表示说话人不耐烦的情绪或者使要求变得更加强烈。

1. Do stop talking! 别说话啦!

2. Do shut up! 闭嘴!

PEG(p.127)对这种用法do进行了详细的分析：

“do is placed before the imperative to make a request or invitation more persuasive:

Do come with us (more persuasive than Come with us).

Do work a little harder. Do help me, please.

It can similarly be used as an approving or encouraging affirmative answer to someone asking for approval of, or permission to do, some action: Shall I write to him? Yes, do or Do alone."

(“do 放在祈使句的前面,可使请求或邀请更有说服力:

同样，在有人请求同意或允许做某事时，do也可以用作赞同或鼓励的肯定回答语：

这就是说,PEG 的作者是肯定而明确地把此种用法的 do 划为加强祈使句语气的助动词的。由此可以证明,上面的 do 并不是替代词,见 $do^{4}$ 。

我们大家都知道,do 可用作替代词(pro-form),代替前面提到的动词及其连带成分,以避免重复:

1. Do you smoke? ——Yes, I do. (do 代替 smoke) “你吸烟吗?”“是的,我吸烟。”

2. Tom speaks a lot. Yes, he does. 汤姆说得很多。是的。(does 代替 speaks a lot) 我们也都知道, do 常常用在祈使句中, 以加强祈使句的语气:

3. Please! Do be quiet a moment. 请静一会儿。

4. Do have some more tea. 请再喝些茶吧。

那么,问句中的 do(please)到底属于上面的哪种用法呢? R. Quirk 等人把这种用法的 do 归到上面的第二种用法,称之为与祈使句连用的 do 的省略形式。并举了下面的例句:

A: Should I open the door? B: Yes, do. A: 我应当打开门吗? B: 是的, 请打开吧。

这里的 do = do open the door。因此，[问]句中的 do please = do please talk about English names。

do 和 make 能够互换的情形是很罕见的。一般地说，do 和 make 都有其固定搭配。只能逐个记忆。下面是一些常用的搭配：

do one's homework(做家庭作业), do business with(与……做买卖), do an experiment(做实验), do harm(伤害), do a favour(帮忙), do damage to(损坏), make a mistake(犯错误), make a noise(弄出声), make money(挣钱), make an effort(做出努力), make an offer(建议), make a suggestion(建议), make advances(取得进展), make an appointment with(与……约会), make a decision(做决定), make haste(赶忙), make a joke(开玩笑), make progress(取得进步), make a trip to(旅游), make contributions to(做贡献), make a promise(允诺,承诺)。

1. It will ____ you good to have some outdoor exercise.

A. make B. do C. be D. feel(全国高考)

2. Will you ____ me a favour, please? A. give B. make C. do D. bring (全国高考, 91 - 11)

3. Although Henry Ford built his first handmade car in 1896, he did no real progress in developing the automobile until 1903. (TOEFL)

4. Prototypical oboes $\frac{\mathrm{did}}{\mathrm{A}}$ a loud, harsh tone, but the modern $\frac{\mathrm{oboe}}{\mathrm{C}}$ is appreciated for its smooth and beautiful tone. (TOEFL)

5. The way of reasoning whereby people do conclusions by logical inference from given premises is called the deductive method. (TOEFL)

6. The fundamental problem of a tax system is to do enough money to pay for the expenses of government. (TOEFL)

此题的改法应当是将D项的is改为does。统观全句句意可以看出，句中的it指代的是his policy。它的谓语本应使用works，但是，根据惯用法，此处要使用替代词does来代替它。请对比下列有关do用作替代词的实例：

1. He earns a lot more than I do. 他赚得比我多得多。

2. My secretary worked later than I did at the office. 我的秘书比我下班晚。

[句意]为了他能再次当选,最重要的并不在于他的政策行之有效,而在于公众相信他的政策行之有效。