25. lest 唯恐(引导条件状语从句，从句中谓语多由should构成虚拟语气，有时省去should用动词原形)
She began to be worried lest he should have met with some accident. 她开始不安起来，唯恐他发生什么事。
He was watching me or something for an hour or two, drawing back the curtain so little lest I catch him, but I saw his face, and I think I can see now the anxiety upon it, the worried impatience. 我看见他正从窗口朝外张望。有一两个钟头，他大概一直在留神我的动静；他只把窗帘掀开一点儿，生怕我发现他，但我还是看到了他的脸。我觉得现在我还能看到他脸上的忧虑神情，那种担心而且焦急的神情。
26. neither … nor 既不……也不(可连接两个主语、宾语、表语、谓语和状语)
But neither the nursery nor the motel my parents bought later had provided enough income to send my sister and me to college. 然而，无论是托儿所还是我父母后来购买的汽车旅馆都不能提供足够的收入供我和妹妹上大学。
I have neither property nor money. 我既没有什么家当也没有钱。
There will be neither rest nor tranquility in America until the Negro is granted his citizenship rights. 直到黑人被赋予公民权美国才会有歇息和安宁。
She neither ate nor drank. 她不吃也不喝。
Tom just came at the right time, neither too early nor too late. 汤姆来得正是时候，不早也不晚。
27. nevertheless 然而；尽管如此，仍就(引导并列从句，表示转折)
Nevertheless, perhaps people should not be spending so much of their time in front of the TV. 然而，或许人们不应花那么多的时间看电视。
There wasn't any news, nevertheless, she went on hoping. 尽管没有任何消息，但她仍抱有希望。
28. no matter 不管怎样(后接疑问词)
For me, teaching is a redeye, sweatypalm, sinkingstomach profession. Redeye, because I never feel ready to teach no matter how late I stay up preparing.对我来说，教书是个令人熬红眼睛、手掌出汗、精神沮丧的职业。说熬红眼睛，这是因为我晚上无论备课备到多晚，总觉得备得还不充分。
You know how it is: you pick up something in a restaurant and your teeth turn rotten, no matter how careful you are.你知道这是怎么回事：只要你在饭馆里拣东西吃，牙齿就会被搞坏，你再当心都没有用。
29. no sooner … than 一……就(引导时间状语从句，以No sonner开头的句子要倒装)
The sun had no sooner started to shine than it was clouded over again. 太阳还没有开始出来就被云遮上了。
No sooner had he gone to bed than the telephone rang once more. 他还没到床上电话又响起来了。
30. not only … but (also) 不但……而且(连接两个对等的主语，谓语，表语，宾语，不定式，ING结构，ED结构或分句)
We will not only bring joy into other people's lives, but also, very often, add happiness into our own. 我们不仅要给别人的生活带来欢乐，而且经常给我们自己的生活增添幸福。
12) Nature ［A］ not only gave the Middle Atlantic region fine harbors ［B］ , howerver ［C］ endowed it with ［D］ a firstclass system of inland waterways.
31. now that 既然(引导原因状语从句)
The Russians might come in a few hours and kill them all ——though most of them were already thinking of how they could escape——but in the meantime, for a brief spell, now that the Fuehrer's strict control of their lives was over, they would seek pleasure where and how they could find it.俄国人说不定几小时之内就要打进来，将他们统统杀掉——尽管他们中间大部分人已在考虑如何逃命——但此时此刻，既然元首对他们生活的严格控制已经结束，虽是短暂的片刻，他们也要及时行乐。
32. or else 否则；要不(就)(引导并列从句)
You must go there at once or else you can not be able to come back in time. 你心须马上就去，否则你就赶不回来了。
My brother couldn't concentrate upon his guide books for matriculation of postgraduate very long, he was too tired, ——or else too sleepy. 我弟弟不能集中精力看他的考研书，他太累了——要不就是太瞌睡了。
33. provided (=providing) 以……为条件，如果……的话，只要(引导条件状语从句，有时和that连用)
She could go with us provided that she arrives in time. 她如及时赶到，就会和我们一起去。
I'll go to the U.S.A, provided I have enough money. 只要我有足够的钱我就去美国。
注：provided在正式文体中用得更多。
34. since 自从；因为(引导时间和原因状语从句)
It has been only forty years since television came to control American free time. 电视开始主宰美国人的空闲时间，至今也不过才40年。
Prof. Glom has named them skyscrapers since they seem to be scraping the skies. 格莱姆教授将它们命名为摩天大楼，因为它们似乎已经擦到了天。
It was 3:30 PM on Monday, April 30, 1945, ten days after Adolf Hitler's fiftysixth birthday, and twelve years and three months to the day