逗号 + “Which”
这里的which ，旨在修饰其前面的ideal state，根本无需加逗号。加了逗号，which就是修饰逗号前的整个短语。但如果修饰This is obviously an ideal state，根本说不通。把逗号去掉，改为;
This is obviously an "ideal state" which cannot be achieved within a decade or a century.
Also, in the field of academy, there was an undercurrent of anti-intellectualism which was especially against science and technology; more accurately, American youth were against the overdevelopment of science. 【有小修改】
We can say that all men are involved in a “big whirlpool” which is continuing to expand.
Hartford continues to lose its industrial base, which means that more and more of its income base depends on companies whose primary business is paper shuffling.
Hartford continues to lose its industrial base, an economic catastrophe in the making [summative modifier], since income is derived primarily from companies engaged in paper shuffling.
Over the years, there are some deficiencies and even defects in our political system which hinders the system of CPC Congress from functioning effectively.
Over the years, deficiencies––even defects––in our political system have prevented the Party Congress from functioning effectively.
For a long time, the flaws of the system of the Party Congress have hindered the well-functioning of the system which can be seen from the following aspects:
For a long time, the Party Congress’s functions have been hampered by major institutional weaknesses and flaws (as follows):
Macbeth was very ambitious. This led him to wish to become King of Scotland. The witches told him that this wish of his would come true. The king of Scotland at this time was Duncan. Encouraged by his wife, Macbeth murdered Duncan. He was thus enabled to succeed Duncan as king. （55字；6句）
Encouraged by his wife and desire kindled by the witches’ prediction, ambitious Macbeth murdered Duncan and became King of Scotland. （19字；1句）
In America, our heroes have customarily run to men of large accomplishments. But today this college and country honours a man. His contribution is not to our size but to our spirit. It is not to our political beliefs, but to our insight. Similarly, it is not to our self-esteem, but to our self-comprehension. . . .
I look forward to a great future for America. This is a future in which our country will match its military strength with our moral restraint. Our wealth will also be in accordance with our wisdom. In addition, our country’s power will also be aligned with our purpose. I look forward to an America which will not be afraid of grace and beauty. Instead, it will protect the beauty of our natural environment and preserve the great old American houses and squares and parks of our national past. What’s more, our America will build handsome and balanced cities for our future.
In America, our heroes have customarily run to men of large accomplishments. But today this college and country honours a man whose contribution was not to our size but to our spirit, not to our political beliefs but to our insight, not to our self-esteem, but to our self-comprehension. . . .
I look forward to a great future for America, a future in which our country will match its military strength with our moral restraint, its wealth with our wisdom, its power with our purpose. I look forward to an America which will not be afraid of grace and beauty, which will protect the beauty of our natural environment, which will preserve the great old American houses and squares and parks of our national past, and which will build handsome and balanced cities for our future.
President John F. Kennedy: Remarks at Amherst College, October 26, 1963
勘误：上一篇有关连词的讨论，经 Husbronick 博友的提醒，第一个例子需要更正：
He believes that the world is divided into two cultures: one is sciences, and the other is humanities, but the two cultures can’t talk to each other, and the situation seems to be worsening.
He believes that the academic world is divided into two cultures: science and the humanities, between which
多谢 Husbronick 博友！