定语从句和强调句有什么区别?

定语从句是由关系代词和关系副词引导的从句，其作用是作定语修饰主句的某个成分，定语从句分为限定性和非限定性从句两种。状语从句分为时间状语从句，结果状语从句，让步状语从句，原因状语从句，条件状语从句以及行为方式状语从句。名词从句包括主语从句，宾语从句，表语从句和同位语从句及there be句型。

一、 限定性定语从句

1. that即可代表事物也可代表人，which代表事物；它们在从句中作主语或宾语，that在从句中作宾语时常可省略关系词，which在从句中作宾语则不能省略。而且，如果which在从句中作“不及物动词＋介词”的介词的宾语，注意介词不要丢掉，而且介词总是放在关系代词which的前边，但有的则放在它原来的位置

2. which作宾语时，根据先行词与定语从句之间的语义关系，先行词与which之间的介词不能丢

3. 代表物时多用which，但在带有下列词的句子中用that而不用which，这些词包括all, anything, much等，这时的that常被省略

4. who和whom引导的从句用来修饰人，分别作从句中的主语和宾语，whom作宾语时，要注意它可以作动词的宾语也可以作介词的宾语

5. where是关系副词，用来表示地点的定语从句

6. when引导定语从句表示时间

〔注〕值得一提的是，表示时间“time"一词的定语从句只用when引导，有时不用任何关系代词，当然也不用that引导

By the time you arrive in London, we will have stayed there for two weeks.

I still remember the first time I met her.

Each time he goes to besiness trip, he brings a lot of living necessities, such as towers, soap, toothbrush etc.

7. whose是关系代词，修饰名词作定语，相当于所修饰成分的前置所有格

8. 当从句的逻辑主语是some, any, no, somebody, anybody, nobody, something, anything, everything或nothing时，常用there is来引导

二、非限定性定语从句：非限定性定语从句的作用是对所修饰的成分作进一步说明，通常和主句间用逗号隔开，将从句拿掉后其他部分仍可成立

1. which引导的非限定性定语从句来说明前面整个句子的情况或主句的某一部分

2. 在引导限定性定语从句时，that有时相当于in which, at which, for which或at which

Attitudes towards daydreaming are changing in much the same way that(in which) attitudes towards night dreaming have changed. 人们对白日做梦的态度正在改变，这与人们对夜间做梦的看法的变化有非常相似之处。

I like the music for the very reason that(for which) he dislike it. 我出于某种原因喜欢这种音乐，而他恰恰与我相反。

We arrived the day that(on which) they left. 刚好我们到的那天他们走了。

3. 有时as也可用作关系代词

4. 在非限定性定语从句中，不能用that，而用who, whom代表人，用which代表事物

常考的强调句结构是it 引导的句子。
It is (was) 被强调部分+ that (who) + 句子其他部分。

此结构强调的成分仅限于主语，宾语和状语。
It is from the sun that we get light and heat.
It was not until I had read your letter that I understood the true state of affairs.

典型例题
1） It was last night ___ I see the comet.
A. the time B. when C. that D. which
答案C. 强调句的结构是： It +be +强调部分 + that (who) + 主谓句。 强调句的连词只有两个，that和who。当强调的部分是人，且为句子的主语时，才用 "who"，其余用that。

原句： My father did the experiment in the lab yesterday evening.
强调主语： It was my father who did the experiment in the lab yesterday evening.
强调宾语： It was the experiment that my father did in the lab yesterday evening.
强调时间： It was yesterday evening that my father did the experiment in the lab. (注意不用when)
强调地点： It was in the lab that my father did the experiment yesterday evening.

2）It is ten years ___ Miss Green returned to Canada.
A. that B. when C. since D. as
答案C. 考点是连词用法。 本题易误选为A. that. 其实本句不是强调句。若是，去掉It be… that还应是一个完整的句子。而本句去掉 'It is…that'，只剩下ten years Miss Green returned to Canada. 不成句。因此本句不是强调句。
It is /was +时间+ since… 其中is<---> has been was <---> had been.