i think that the doctor had better see you

~ I think that the doctor had better see you.
首先对句子成分做分析。
这是一个含有宾语从句的复合句。
主句是 I think that,从句是that 引导的 the doctor had better see you.
其中that 是宾语从句的先行词，充当主句谓语动词think的宾语，在从句中是不充当任何成分的。
在这个句子里面that可以省略不用。
要用从句的情况很多，可以查阅资料，百度文库有很好的学习资料。
以此题为例来说说需要用从句的情况：通常能用一个简单句
(只有一个主语，一个谓语，一个宾语)把意思表达清楚，就不需要用从句，但是很多情况下，一个简单句无法把意思表达情况，需要用到很多简单句，此时复合句就方便多了，一个复合句就能说情况。
例如：我昨天看到了帮助小女孩的那个人。
I saw the men who helped a girl.

就是所表达的意思词和短语都不能满足了，就得用句子，如这句，I think 

是主句，后面的句子就是从句了，这个是宾语从句。

I think that the doctor had better see you. 我认为那个医生最好是来看看你。
---好牛啊，你在威胁医生吗？从逻辑上似乎应该说：I think that you'd better see a doctor. 我觉得你最好去看看医生。口语中通常会把关联词that省略。这句话涉及两个主语，用从句是再自然不过了。一般涉及多主语、陈述完整事实以及直接引语等场合会用从句表达，使句子结构富有层次感，很类似编程时的子程序或方法调用。实在不想用从句的话，还有不定式与分词，如 I advise you to see a doctor.我建议你去看医生。

think是动词,在完整的句子中动词后面需要接宾语；因为本句宾语the doctor had better see you是一句不缺成分的句子,而动词不能直接接句子形式的宾语,但是可以接宾语从句,所以这里使用that去引导这样的一个宾语从句；一般书面语法要求是需要加that的,而口语中有时会被省略

我想医生最好见你。

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那坡县18980756581： 我认为电脑是最有用的发明.I think that the computer is the_____ - invention. - ？
蓬疯右旋：[答案] 答案:most useful.这里是说最有用的用最高级,形容词有用的useful是多音节单词,最高级加上most,故答案是most useful.

那坡县18980756581： i think that是什么从句 - ？
蓬疯右旋： I think that,that引导宾语从句.I think that the underlying problem is education, unemployment and bad housing. 我认为深层的问题在于教育、失业和糟糕的住房条件.I think that the main thing to do is get creative, happy people. 我觉得主要是要聘...

那坡县18980756581： I think that the doctor had better see you.帮详细分析下这句话的句子成份或结构好么? - ？
蓬疯右旋：[答案] I 主语 think 谓语 that 引导词 the doctor had better see you.宾语从句 the doctor 宾语从句的主语 had better 宾语从句的状语 see 宾语从句的谓语 you 宾语从句的宾语 【俊狼猎英】团队为你解答.

那坡县18980756581： I think that the first thing 跟to do 还是 being done?I think that the first thing - ____ - is to relax yourself - ？
蓬疯右旋：[答案] 跟 to do .因为这件事还没有做呢

那坡县18980756581： I think that the poor health has s__ - to do with his bad diet habits - ？
蓬疯右旋：[答案] something

那坡县18980756581： 英语翻译I think that the most basic and powerful way to connect to another person is to listen.Just listen.When people are talking ,there's no need to do ... - ？
蓬疯右旋：[答案] 我觉得与别人沟通最有效的方式就是倾听,只要倾听就可以了.当别人在讲话时,除了接受他们所讲的没有必要再去做其它事... 我仅仅倾听.当他们哭的时候,他们发现我和他们在一起. 这个简单的事情学起来却不简单.它与我小时候所学习的东西相违背....

那坡县18980756581： 英语i think that the docter和i think the docter有什么区别? - ？
蓬疯右旋： 第一个句子think后是宾语从句,第二个句子think后应该是符合宾语吧(你没写完,我也不是很了解整个句子的内容).

那坡县18980756581： 写句子i think+that/whether/if - ？
蓬疯右旋： i think that the apple tastes good. i think whether he comes is critical.i think if you do your homework is important to your final grade.

那坡县18980756581： I think that the doctor had better see you.变同义句I think that it is( )for the doctor( )see you. - ？
蓬疯右旋： I think that it is( better)for the doctor( to )see you.