Obviously, this is an “ideal realm”, which we may not reach in a decade or even in acentury.

改译：

Obviously, this is an ideal situation (which is) impossible to achieve within adecade or even a century.

注：括号中的 which is 可略。见下文说明。

“who is”、“which was”通常多余，可以删除：

原句改为

His brother, who is a member of the same firm
His brother, a member of the same firm
Trafalgar, which was Nelson's last battle
Trafalgar, Nelson's last battle

WHICH 不是灵丹妙药，要慎用！

见以下说明：

He washed all the flasks, and then he locked up the lab.[2]

and 表示句子增加了信息。But 则意味着行为的逻辑顺序有所调整。什么时候用and，什么时候用but，取决与作者意图。

如果改为

(1) He washed all the flasks, then he locked up the lab.

(2) After he washed all the flasks, he locked up the lab.

或

He washed all the flasks before he locked up the lab.

(1) 强调各环节顺序（先洗水壶，然后把实验室锁上）；(2) 则强调洗水壶的行为（washing up the flask）

再次强调：很多时候，如果不用 which，效果会更好：

例：

着重的是要改变人类的教育，使习科技的不成为“机器人”，习人文的了解“科技”的性质。

原译：

The most important solution is changing the education pattern which will notlead a hi-tech student to a robot and will make a philosophy student know thenature of science.

改译：

The focus should be to change our education, so that 【体现因果关系】science learners do not become “machines” and humanitieslearners will have some knowledge of science.

本文作者周蕴仪是新加坡人，现在北大和北外兼职教授翻译，中英文俱佳。

学生经常使用which把不同的意群连接起来。也许因为觉得这些意群确实有关联，也许以为句子加长后的效果更好。然而，用which存在各种“风险”，如不慎用，会导致误解，或影响文章的流畅性。比如：

First, we had lunch and then our guide told us the secret of the cave, whichpleased me. [1]

句子中有一系列的动作、感受，我们不知道到底什么原因使作者感到 pleased。是the cave’s secret吗？是因为guide 抖出秘密？是 lunch？是因为秘密在吃过午饭后才被抖出（had lunch and then our guidetold us…）？Which 到底所指为何？

如果你之所以高兴，是因为导游在你吃过午饭后才抖出秘密，句子可以改为

I was pleased that the guide waited until after lunch to tell us the secret.

如果是因为听了该山洞的秘密而让你高兴，则可改为

I was pleased with the secret of the cave, which the guide told us after lunch.

还用前一篇原文（《余英时和吴大猷对话》）为例。

1、一九六零年代中叶起，越战期间，美国的年轻人掀起了反越战、反建制（anti-establishment）的风潮（所谓‘嬉皮’风气，只是消极性的一种反抗，没有积极性建设的思想），在学术上也有反智（anti-intellectualism）的暗潮。

From the mid-1960s, especially during the Vietnam War, American youngstersstart an anti-Vietnam War and anti-establishment campaign (the so-called hippieculture, which was just a passive resistance without positive creativity).

改译：

During the mid-1960s, in the midst of the Vietnam War, American youth launchedanti-war and anti-establishment campaigns (the so-called hippie culture wasmerely passive resistance without constructive contribution).

注：此段需要进一步修改。不过为说明which 的问题，所以保持原译的主要面目。删除原译的which，意思一目了然，句子也更加通顺。

2、当时开始有很多人注意到环境、卫生、生态等问题，造成压迫政府在日后订定了许多法律，保护环境，防止污染。限制学府中接受政府中国防系统支持之科学研究计划等。

At that time, many people began to pay attention to some problems ofenvironment, sanitation and ecology, which put pressure on the government tolegislate for the preservation of environment and against pollution.

改译：

When people became aware of the environmental, health and ecological problems,the government was pressured into enacting legislation to address the problems.

3、经济愈繁荣生活水准愈提高，人的要求也愈高，只能往上长，不能往下收缩，维持不变都认为不可。

Prosperity of economy raises the standard of living, which is associated withthe higher requirement from people who hope to live better and better, whocannot stand living standards going from bad to worse, or even no change nochange of living standard.

改译：

As part of human nature, when the standard of living rises with economicdevelopment, expectations go up. Expectations will never come down. Evenremaining at status quo is unacceptable.