在定语从句，大家知道occasion的用法？放在句子的哪里呢？
occasion在定语从句中作先行词时，后面用关系副词when还是where
occasion在表示：“a particular time or instance of an event（特定的）时刻；场合”时，定语从句引导词用when；当表示：“a special or noteworthy event, ceremony, or celebration（仪式、庆典等）重大场合”时，定语从句引导词用where。（新牛津英汉双解大词典）
例句：
1. In hard times, the Spring Festival was the only occasion where a family threw off the old attire and put on new clothes specially made for the festival.
2. Describe an occasion when you had to give a presentation to an audience.
例题：
D1. Occasions are quite rare ____ I have the time to spend a day with my kids.
A. whoB. whichC. whyD. when
定语从句的十大考点：
1. that 与which 在指代物时的用法区别
that 和which都可以引导先行词为物的定语从句，但是用法有区别：
① 只能用that的五种情况
a. 先行词为不定代词或先行词由不定代词修饰时
b. 先行词前有最高级或序数词修饰时
c. 先行词即有人又有物时
d. 先行词前有the very, the only修饰时
e. 主句为which,或who 引导的特殊疑问句时
② 只能用which的两种情况
a. 非限定性定语从句中
b. 介词之后引导定语从句时
2．which与as的区别
as 和which 都可以引导非限制性定语从句，三种情况下只能用as，不能用which
a. as置于句首引导定语从句时（As we know,…）
b. as 含有“正如”之意（…as we expected）
c. 先行词前有such, the same 修饰时（…such an easy question as the little boy can answer.）
3. who、whom、that 的区别
a.先行词为those或people 时，常用关系代词who,不用that
b.介词之后用关系代词whom引导定语从句
4. whose 用法
whose+n. 引导定语从句的结构是定语从句的一个考查热点，此结构可以换成是the+n.+of+which引导定语从句或者可以换成是of which +the+n.
man pulled out a gold watch, the hands of which were made of small diamonds.
whose hands / of which the hands
5. 介词+关系代词引导定语从句的`用法
a. 介词之后的关系代词只能用which（先行词为物）或者是whom（先行词为人）
b. 介词的选择方法有三个原则：一“先”二“动”三“意义”
I lost my pen, with which I took notes. (先行词为pen,使用钢笔用with)
This is the house in which he lives. (定语从句中谓语动词live为不及物动词)
The gas is oxygen without which we can’t live. (根据句意决定)
6. 先行词为way时
先行词为way，在定语从句中作状语时，用that，in which引导定语从句，也可以省略关系词。
e.g. I don’t like the way(that/in which) he speaks to his parents.
7. 关系副词when、where、when引导定语从句的具体用法
① 先行词表示时间、地点、原因时，在定语从句中作状语，选择相应的关系副词when、where、why引导定语从句。若其在定语从句中作主语或宾语，则选择关系代词引导定语从句。区别三组例句：
where he lives.
a. This is the place
that/which he visited last year.
when my brother was a little boy.
b. I still remember the time
that/which we spent together.
why he was late.
c. This is the reason
that/which he gave us.
②某些非地点时间名词有定语从句修饰，关系词在从句中作状语，由where引导定语从句（stage, case, point, situation）；同样用法的还有occasion,由when引导定语从句。
e.g. I can think of many cases where students know a lot of words but don’t write a good essay.
There are many occasions when people don’t know what they want.
8. 定语从句中的谓语动词
关系代词在定语从句中作主语时，定语从句中的谓语动词应该与先行词保持一致。
e.g. Anyone who wants to have a holiday puts up your hand.
Those who want to have a holiday put up your hand.
This is one of the students who have passed the exam.
This is the only one of the students who has passed the exam.
9. 区分定语从句和其他句型
①区别于简单句和并列句
most of whom are boys. (定语从句)
There are 70students in our class , and most of them are boys. （并列句）
Most of them are boys. （简单句）
②区别于强调句型
It is in the factory that he works. (强调句型)
It is the factory where he works. （定语从句）
It is in the classroom (where we have classes) that the meeting will be held.
(定语从句修饰先行词the classroom)
(强调句型，强调部分为介词短句in the classroom)
③区别于同位语从句
that she had passed the exam （同位语从句：对名词解释说明）
The news excited us.
that he told us （定语从句：对名词修饰限定）
④区别于状语从句
Do you know the time when the class is over? (定语从句，有先行词)
Let’s play games when the class is over.（时间状语从句，无先行词）
Put the book where it belongs. (地点状语从句，无先行词)
10. 定语从句中关系词的省略
定语从句中，作宾语的关系代词可以省略，介词之后的关系代词不可省略。
This is the house which he lives in. (√)
This is the house he lives in. (√)
This is the house in which he lives. (√)
This is the house in he lives. (×)
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