有这样一道单选题：
Although _________A_________ my opinion, the old professor didn’t come up with his own.
A. against B. on C. for D. in
此题答案选A。根据句首的although可知，前后两者句意思相反，故against。全句意为：虽然老 教授不同意的观点，但他也提不出自己的观点。句中的although against my opinion为although he was against my opinion之省略，为“连词+省略结构”的一种。这类结构归纳起来主要有以下几 种类型：
一、连词+介词短语
While at college, Delia wrote a novel. 上大学时，迪莉娅写了一部小说。
Once in the examination hall, he forgot about all this. 他一进考场，这一切他都忘了。
While in London, he studied the English labour movement. 在伦敦时他研究了英国的工人 运动。
二、连词+形容词
He acted as if certain of success. 他表现得对成功很有把握似的。
If possible, let me know beforehand. 如果可能，可在事前通知我。
Though exhausted, he stayed up late. 尽管疲惫不堪，他仍很晚才睡。
Whenever possible, the children play outside. 每当可能，孩子们总在外边玩耍。
Avoid structures of this kind wherever possible. 只要可能，都要避免这种结构。
Her daughters were of some help, however small. 她的女儿们总能帮些忙，不管多小的忙。
三、连词+现在分词
She tremble a little while doing so.
她这样做时稍稍颤抖了一下。
He tends to get carried away when watching wrestling on TV.
他一看电视中的摔跤就很兴奋。
They were surprised by her openness when talking about her private life.
她谈起私生活时非常坦率，大家都很吃惊。
注：以下两句中的before不是连词，而是介词，其的-ing动词为动名词，而非现在分词：
Before giving evidence the witness had to take an oath.
证人作证前要先宣誓。
It would be unwise to buy the house before having it appraised.
买房子不事先估价是不明智的。
四、连词+过去分词
He will come if asked.
他如被邀就会来。
When asked, she confirmed that she was going to retire.
有人问她时，她肯定了她将要退休。
While locked up in prison, she wrote her first novel.
她在狱中写出了第一部小说。
When taken according to the instructions, the drug has no side effects.
若按说明服用，本药无任何副作用。
五、连词+不定式
Success in business is simply a matter of knowing when to take a chance.
商业上的成功就在于把握时机。
Smiling pleasantly, the stranger turned as if to speak to me.
那个陌生人面带愉悦的笑容，转身向我，似乎想对我说话。
【温馨提示】
1. “连词+省略结构”通常可视为一种紧缩的状语从句，即认为是省略了从句的主语 (与主句主语一致)和主语后的动词be。如：
Look out for car’s when (your are) crossing the street.
过街时注意车辆。
He acted as if (he was) certain of success.
他的举止就像一定会成功一样。
有时可视为省略了it is(其中的it并非主句主语)。如：
lf (it is) possible, please let me know by this evening.
如果可能的话，请在今晚以前告诉我。
Where (it is) necessary, improvements will be made.
哪儿需要，就在哪儿改进。
2. 并不是所有的状语从句都可以用以上办法来紧缩的，如原因从句就不能用这种办法来处理。
3. 与上面提到的省略结构相似且经常在高考中出现的还有if not…这一种形式。如：
His pronunciation, if not good, is at least tolerable.
他的发音如果说不算好，也还过得去。
If not today, tomorrow I’m sure you’ll get an answer.
如果今天得不到回信，明天准能得到。
Usually, if not always, we write “cannot” as one word.
我们即使不总是如此，也通常是把cannot作为一个词来写的。
This is one of the oldest buildings in town, if not the oldest.
这是城里最古老的房屋之一，如果不是最古老的话。
