about

有区别。在谈到非科学性、非严肃性问题时，一般使用 about。因此，正像 R. Quirk 等人所说的那样，在 chat 或 quarrel 一类动词之后使用 on，是不合适的：

1. That at least is my idea about friendship. (Wilde) 这至少是我关于友谊的看法。

2. They are divided in their opinions about it. (Sinclair) 他们对于这件事的看法有分歧。在谈到科学性或严肃性的问题时，常常使用 on。on 主要用于有准备的正式语言交流

(演说、讲课、写作等):

1. My father is delighted with my second article on Shakespeare. (Yeats) 我父亲对我的第二篇论莎士比亚的论文很高兴。

2. An artist was hired to illustrate a book on birds of the world. (MD) 雇了一名画家来给一本关于世界鸟类的书作插图。

LDCE 举出了很好的实例来说明 about 与 on 的区别：

a book on rabbits(一本论兔子的书——一本科学著作)

a book about rabbits(一本关于兔子的书——可能是一本给儿童看的故事书)

She spoke on butterflies. (A)

She spoke about butterflies. (B)

CGEL 说, 句(A)会使人感到她在发表正式演说(gave a lecture on), 而句(B)则可能是非正式的谈话或是偶然谈到(§9.60)。

类例：

1. Think the matter over and we'll speak about it in the morning. (Barrie) 认真考虑一下这件事,我们明天上午将谈论它。

2. That is a subject that mustn't be spoken about. (Eckersley) 那是个不许谈论的话题。

3. At our next meeting Dr. J. B. Whiteley will speak on 'the Effects of Alcohol on the Heart'. (Wood) 在我们的下次会议上, J. B. 怀特利医生将就酒对心脏的影响这个问题做报告。

4. The professor thanked the audience for listening to his ____ on Shakespeare.

A. lecture B. conference C. rehearsal D. recital(Nelson. 45B)

它们在语义上并没有什么区别,都表示最近的将来(正要,刚要)。但是,在语法上,be about 应与带 to 的动词不定式连用,而 be on the point of 则必须接动名词。

1. He was just about to dive when he saw the shark. (PEG) 他刚要跳水,突然看见了鲨鱼。
2. He fears that he is about to have a heart attack. (EDECT) 他害怕心脏病要发作。
3. The roof seems on the point of falling in. (ECD) 屋顶眼看就要塌下来了。
4. I was on the point of communicating with him by paper. (EDECT) 我正要写信跟他联系。

半助动词 be about to (+ 动词原形), 如同 will/shall, be going to, be to 一样, 也能表达将来时间。但是 be about to 与它们有一个重要的区别, 就是它表达的是最近的将来, 意思相当于 be on the point of + 动名词或 be going to + just (“正要” “马上就要”)。I’m about to read your essay. ≈ I’m just going to read your paper. (CGEL)。如同 was/were to 和 was/were going to 表示过去的将来时间一样, was/were about to 也可以表示过去的将来时间。

1. Mrs. Gerhardt was about to begin, but Jennie spoke first. (Dreiser) 杰哈特夫人正要开始讲话，珍妮却抢先发言了。

2. He met her in the doorway just as she was about to go away. (Galsworthy) 正当她要离开时,他在门口遇见了她。

3. Just as Collet was about to divide his men to search the basement and grounds behind the house, he heard voices on the level above them. (Dan Brown, The Da Vinci Code) 科莱正打算派手下到地下室以及屋后面的空地里去搜查，这时，他听到楼上有声音。（《达·芬奇密码》）

关于 be about to... when 见 when $^{10,11}$ 。

上面两个句子都是正确的。但句(a)用于正式语体,是英语规定语法学家所坚持的用法。但是,这种在限制性定语从句中把介词放在关系代词之前的用法,常常使人感到生硬。所以,在非正式语体中,句(b)的用法更为常见。对于各类考生来说,只需知道在限制性定语从句中两种用法都是正确的,就足够了,没有必要去深究孰优孰劣的问题。

这类可以放在定语从句末尾的介词,并不是很多的,大都是字母少的介词,而且以表示空间的介词为主(in, at, on, under, for, of 等):

1. $\left\{ \begin{array}{l} \text{This is the house in which I lived for ten years.} \\ \text{This is the house which I lived in for ten years.} \end{array} \right.$ 这是我住过十年的房子。

2. $\left\{ \begin{array}{ll}\text{the table under which the boy crawled}\\ \text{the table which the boy crawled under (CGEL)} \end{array} \right.$ 男孩在下面爬的那张桌子

3. $\left\{\begin{array}{l} the lady towards whom the dog ran \\ the lady who(m) the dog ran towards(同上)\end{array}\right.$ 狗朝着她跑过去的那位女士

4. $\left\{\begin{array}{l} the office at which he works \\ the office which he works at \end{array}\right.$ 他工作的办公室

5. $\left\{\begin{array}{l} the day on which she was born \\ the day which she was born on \end{array}\right.$ 她出生的那天

6. $\left\{\begin{array}{l} I have read the poem of which she is speaking. \\ I have read the poem which she is speaking of. \end{array}\right.$ 我读过她正在谈论的那首诗。

应注意,在非正式语体中,当介词位于定语从句末尾时,关系代词常常省略。(参见which ... in)