take a seat在句子中是宾语补足语，关于宾语补足语的说明如下：
有些及物动词带了宾语后还需要有一个补足成分才能使句子完整，这个补足成分就叫做宾语补足语。用来说明宾语的行为、特征、状态、身份等。宾语和宾补一起构成复合宾语。主要有下面几种类型：
1. 名词（或代词）+名词
She found him a very clever boy.
2. 名词（或代词）+形容词
He had a strange way of making his class lively and interesting.
3. 名词（或代词）+副词或介词短语
Last Sunday I saw you out with your sister.
To her surprise, she found herself in a different world.
4. 名词（或代词）+分词（分词短语）
I saw him doing his homework when I passed his window.
I was absent-minded when I heard my name called.
注意：
在用现在分词或不定式作宾语补足语的动词中，有些只能用现在分词作宾语补足语；有些只能用不定式作宾语补足语；还有的动词既能用现在分词又可用不定式作宾语补足语：
1）、只能用现在分词作宾语补足语的动词有：catch, keep, mind, prevent, stop(阻止)等。
She caught her son smoking a cigarette.
His words started me thinking.
2）、只能用不定式作宾语补足语的动词有：wish, desire, expect, love, prefer, trust, encourage, let, allow, permit, mean, lead, bring, put, hurry, cause, remind, ask, invite, beg, request, worry, advise, persuade, call on, tell, order, command, require, make, force, drive, forbid, warn, help, teach, show, assist, report, bear, wait for, think, take, know, judge, consider, suppose, believe, allow, prove, declare等。
Their parents don’t allow him to stay out late.
他父母不允许他在外面呆到很晚。
3）、既能用现在分词又可用不定式作宾语补足语的动词有：see, watch, notice, look at, observe, listen to, hear, feel, have, imagine, discover, like, want, understand, hate, get, set, leave等。
She was seen running away from the scene of the crime.
有人看见她从犯罪现场跑开。
I saw you put the key in your pocket.
我见你把钥匙放进了口袋。
5. 名词（或代词）+不定式
1).to do
The villagers did not allow them to build a factory there.
（ask tell beg force wish want expect advise permit order persuade）
2) 省略 to 的不定式
使用不定式作宾语补足语时，不定式符号 to 的取舍问题：
1）、在hear, listen to, let, have, make, see, watch, notice, observe 等动词后的不定式需省去 to 。
2）、feel 一词，跟 to be 型不定式带 to；跟 to do 型不定式不带 to。
3）、help 一词后的不定式，可带 to，也可以不带 to。
6. 名词（或代词）+从句
We will make our hometown what your hometown is now.
7. 常见with+复合宾语有下列几种形式：
1） with＋名词／代词＋形容词
It is not good manners to speak with your mouth full．
满嘴食物去说话是不礼貌的。
2） with＋名词／代词＋副词
The city looks more beautiful with all the lights on．
所有的灯亮起来，这座城市看起来更漂亮了。
3） with＋名词／代词＋介词短语
The woman with a baby on her back lives downstairs．
这个背着婴儿的妇女住在楼下。
4） with＋名词／代词＋不定式，不定式表示主动、将来的动作。
With you to help us, we are sure to finish the work on time．
有你来帮忙，我们会按时完成任务的。
With so much work to do, we can’t kill any time by playing cards．
有这么多工作要做，我们没有时间打扑克。
5）with＋名词／代词＋-ing形式，-ing形式表示主动或动作正在进行。
With a boy leading the way, they started towards the village．
由一个男孩带路，他们朝那个村子走去。
6） with＋名词／代词＋过去分词，过去分词表示被动或动作已经完成。
With the problems settled, we all felt very happy．
问题解决了，我们都感到很高兴。
7）with＋名词／代词＋名词
China is a great country, with its capital Beijing.
中国是一个伟大的国家，首都是北京。
8. 结构：主+谓语+ it +宾补+真正宾语
I found it pleasant to be with your family.
We think it out duty that we should help the poor.
在复合宾语中，宾语通常为名词或代词，但有时也可以用不定式（短语）、动名词（短语）或that从句来充当。这时，应使用先行it代替宾语，而将真正的宾语移到句子的后部，如：
I felt it necessary to speak about our shortcomings.
Do you consider it any good trying again?
We all thought it a pity that you couldn’t join us.
注意：在这种结构中，宾语补足语通常为名词或形容词；常用于这种结构的动词有： feel, find, think, make, take, judge, consider 等。 第二个句子，You are giving a reason that you know is not really good enough to explain what you did．红色部分加绿色部分是定语从句，用来修饰reason的，其中后面的绿色部分，是know的宾语从句． |
