关系代词which在非限制性定语从句，中所指代和修饰的可以是主句中的名词、形容词、短语、其他从句或整个主句或一系列句子，在从句中作主语、动词宾语、介词宾语或表语。该从句一般放在主句后，且用逗号隔开。
1.which指代主句中的名词，被指代的名词包括表示物、婴儿或动物的名词、表示单数意义的集体名词以及表示职业、品格等的名词。
如：
I gave her an interesting book, which she started to read at once. 我给了她一本有趣的书，她马上就读了起来。
（which she started to read at once 是非限制性定语从句，先行词是：an interesting book）
These apple trees，which I planted three years ago，have not borne any fruit.
这些苹果树是我三年前栽的，还没有结过果实。（which 指代These apple trees ）
She is an artist，which I am not.
她是一位艺术家，而我不是。（which 指代an artist ）
Water，which is a clear liquid，has many uses.
水是一种清澈的液体，有许多用途。（which 指代Water）
The two policemen were completely trusted，which in fact they were.
那两个警察完全受到信任，事实上也确实如此。（which 指代The two policemen）
I rewrote his rough draft, which was published under my name
我把他的草稿重新改写，并以我的名字发表了。（which 指代his rough draft）
The lawyers are preparing for the trial, which commences in 30 days. 律师们正在为这场将于30天后开始的审判进行准备。（which 指代 the trial）
Loosen any tight clothing, which may inhibit breathing. 松开过紧的衣服，这类衣服可能会妨碍呼吸。（which 指代 any tight clothing）
He had a knee injury, which put him out of the reckoning. 他伤了膝盖，失去了获胜的可能。（which 指代 a knee injury）
2.which指代主句中的形容词。
如：She was very patient towards the children，which her husband seldom was.
她对孩子们很耐心，她丈夫却很少这样。（which 指代patient）
She is always careless，which we should not be.
她总是马虎大意，我们可不应该这样。（which 指代careless）
3. which指代主句中的某个从句。
如：He said that he had never seen her before，which was not true.
他说以前从没见过她，这不是真的。（which 指代he had never seen her before）
I think Li Hua is a talented student, which makes me ashamed.
我认为李华是一位有才华的学生，这使我很惭愧。（which 指代Li Hua is a talented student）
4. which指代整个主句。
如：
It was raining, which was a pity.那时天下着雨，那是一个遗憾。（which 指代It was raining）
They ran out of drink. Which actually didn't bother me because I wasn't drinking.
他们把酒喝完了。但实际上这对我来说无所谓，因为我不喝酒。《柯林斯高阶英汉双解学习词典》（which 指代They ran out of drink.）
The clock struck thirteen, which made everyone laugh. 时钟敲了13下，这使大家都笑了起来。（which 指代句子 The clock struck thirteen）
The sun heats the earth, which is very important to us.
太阳使地球暖起来，这对我们人类很重要。（which 指代句子The sun heats the earth）
It was built in a year, which seems absolutely incredible. 它在一年内就建成了，这简直难以置信。（which指代句子It was built in a year）
In the presence of so many people he was little tense, which was understandable.
在那么多人面前他有点紧张，这是可以理解的。（which指代句子In the presence of so many people he was little tense）
He may have acute appendicitis，in which case he will have to be operated on.
他可能得了急性盲肠炎，如果是这样，他就得动手术。（which指代句子He may have acute appendicitis）
When deeply absorbed in work，which he often was，he would forget all about eating and sleeping.
他经常聚精会神地工作，这时他会废寝忘食。（which指代句子When deeply absorbed in work）
For example, I got good grades, which made my parents happy.例如，我取得了好成绩，这让我的父母很高兴。（which指代句子I got good grades）
He broke the glass, which made his parents angry.( which指代句子He broke the glass)
Li Ming was late. which made Mr. Zhang very angry.
李明迟到了，这让张老师很生气。
As a result ,my English was quite poor, which made me sad and disappointed.
结果，我的英语很糟糕，这使我很伤心和失望。（which指代句子my English was quite poor）
It was built within a year, which seems absolutely incredible.
它在一年内就建成了，这简直难以置信。（which指代句子It was built within a year）
It provides partners with chances of studying from each other, which will benefit us in the long term.合作提供给合作者们相互学习的机会，这从长远看来将对我们有利。
（which指代句子It provides partners with chances of studying from each other）
This school often provides students with chances of taking exercises, which will benefit students’physical health.
这个学校经常给学生锻炼的机会，这对学生的身体健康很有帮助。
（which指代句子This school often provides students with chances of taking exercises）
Last but not least, you can spare some time to see a Peking Opera before that time, which can help you understand it better.
最后但同样重要的是，你可以在此之前去观看一场京剧，这样能帮助你更好地了解它。
（which指代句子you can spare some time to see a Peking Opera before that time）
特别是最后两种用法高分作文经常可以看见，而阅卷老师也很着迷这种用法，所以同学们在写作文的时候特别是平常考试作文，要放心大胆地把which指代整个主句的用法写进作文里。