It is suspected that... 和 It is doubted that...，无法用正宗与否来衡量这个问题。 

第一个说法可以有，因为主动语态可以说：People suspect that...

第二个说法不正确，因为主动语态就不说：*People doubt that...

此外，既然doubt 表示“怀疑”之意，那么后面的句子应该是表达“悬而未决”的概念。所以，其从句不可能用that 引导，而应该用whether 或if 引导。

that 引导的句子是陈述一个事件；whether 引导的是一个带有“疑问”的句子。

正宗的说法应该是：把doubted 改为形容词doubtful，主句用whether 或if 引导，也可用that引导。例如：

It is doubtful whether he will be able to come.  

It is doubtful if he will be able to come. 

It is doubtful that he will be able to come. 

你查一下语料库便知。

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doubt 的用法：之后应该接什么？

1. doubt 的基本意思是对事〔物〕的真实性等表示“怀疑”或“不信任”,有时甚至在调查研究之后仍“难以确定”。也常用来表示对宗教信条等持有疑虑。

2. doubt 多用作及物动词,可接名词、代词、动名词、带疑问词的动词不定式或that/wh-/if从句作宾语,也可接以“(to be+) n./adj. ”充当补足语的复合宾语。接that从句作宾语时, 含有doubt的主句需用否定或疑问形式。doubt偶尔也用作不及物动词,常与介词of连用表示“对…抱怀疑或悲观的态度”。

3. 在疑问句或否定句中, doubt 的宾语从句应用that引导; 在肯定句中,则应由if〔whether〕引导。

doubt 是表示思想状态的动词,指思维活动的结果,通常不用于进行体。

4. doubt 一般不用于进行体。但偶尔可见如She is always doubting my word.(她总是不相信我的话)这类的句子,句中的现在进行时表示一种“不满”的情绪。

5. 在肯定句中不可以说I doubt so.但在否定句中则可以说I don't doubt so.

在新课标人教版必修二第1单元课文中，有这样一句话：There is no doubt that the boxes were then put on a train for Konigsberg, which was at that time a German city on theBaltic Sea.

在选修六第4单元课文中，也有类似的一句话：There is no doubt that the earth is becoming warmer.

就这两个句子而言，doubt后面的that从句是同位语从句。

网友可能要问，这里，doubt后面的从句为何用that引导，用whether可以吗？为什么下面的句子用whether？

I doubt whether he is at home. 我看他不一定在家。

There is some doubt whether he will come on time. 他能否按时到达不能肯定。

我们发现，用that引导的从句表达了一个陈述而又肯定的事实；用whether引导时则表达了一个带有疑问的情况。那么，在什么情况下由that引导，什么情况下由whether引导呢? 这就要从doubt 的含义说起。doubt一词，无论用作动词还是名词，都表示“怀疑，疑惑”的意思，就是说，当它前面有否定词时，即“没有疑问，毫无疑问”，它的同位语从句就用that引导。反之，就用whether引导。请看下面的例题：

Although most of them have no doubt ______ he will pass the exam, I still think there is some doubt ______ he has really got everything ready.

A. whether; that     B. that; whether       C. that; that       D. whether; whether

答案应选B. 因为：第一个选项之前是no doubt (没有疑问)，既然没有疑问，那么，同位语从句就表达了陈述的含义，故用that；第二个选项之前是some doubt (有些疑问)，那么，同位语从句就表达了带有疑问的含义，故用whether。

不仅同位语从句，而且宾语从句也是如此。试比较：

I doubt whether she will like the present we bought for her.

I don't doubt that she will like the present we bought for her.

下面举一些常见的含有doubt 的例句。

1. There is no doubt 接that从句：

There is no doubt that he will win the election. 毫无疑问,他将在竞选中获胜。

There is no doubt that we will succeed in designing the project. 毫无疑问,我们能把这项工程设计出来。

There is no doubt that such facts exist. 这些事实无疑是存在的。

There is no doubt that our educational system leaves something to be desired.毫无疑问的我们的教育制度令人不满意。

There is no doubt that these two words are spreading in at any rate written usage.毫无疑问这两个词在书面语中用得越来越多。

There is no doubt that she loves him all heart. 毫无疑问,她是全心全意地爱他。

But there is no doubt that Mandela has become its personification.但毫无疑问的是,曼德拉已经成为运动的化身。

There is no doubt that smoking can seriously damage our health.毫无疑问,吸烟会严重损害我们的健康。

However, there is no doubt that she is good at paintings.不过, 毫无疑问,她的画很好。

There is no doubt that you will be warmly welcomed.你肯定会受到热烈欢迎。

2.doubt 之后用whether引导的从句：

I doubt whether Jack could manage a sailing boat. 我怀疑杰克会不会驾驶帆船。

I doubt whether your procedure would be considered regular by authorities. 我怀疑当局是否会认为你的手续合乎规定。

She was in doubt whether she was right. 她对她是否正确拿不准。

I doubt whether he had any real understanding of Shakespeare. 我怀疑他是否真正理解莎士比亚的作品。

On reflection, I doubt whether I was right. 细细想起来我倒怀疑我讲的是否正确了。

There is some doubt whether your people have observed the forms of law, my lord. 阁下,存在着这么一个疑问,就是贵方的人是否遵守了法律的规定? 

I doubt whether the court would decide in his favor. 我怀疑法院能否作出对他有利的判决。

There is some doubt whether he will be elected. 他是否能当选还不太确定。

People began to doubt whether the bill would ever get through. 人们开始怀疑该提案能否通过。

Do you have a doubt whether she will be dismissed from school? 你怀疑她是否能被学校开除吗?

He was tortured by the doubt whether he would accept their presents. 他为是否接受他们的礼物这个疑虑所折磨着。

3.doubt 后接介词about：

There is no doubt about his suitability for the job. 毫无疑问,他适合这个工作。

There is no doubt about his findings.对于他的发现无庸置疑。

There is no doubt about his innocence.他完全是无辜的。

Colours do influence our moods; there is no doubt about it.色彩的确影响我们的情绪，这一点毫无疑问。

In many British industries there is no doubt about the high quality of management.英国的许多工业部门无疑具有较高的管理水平。

He is certainly there; there is no doubt about it.他肯定在那儿, 这是毫无疑问的。

I'm rather in doubt about his explanation of this question.他对这个问题的解释我总是半信半疑。

Nobody has any doubt about that. 对这一点没人怀疑。

There is not much doubt about it. 这是没什么可怀疑的。

There's no doubt about it. He's the one the policemen are looking for. 没错儿, 警察找的就是他。

When in doubt about the meaning of a word, consult a dictionary. 拿不准词义时, 查查词典。

4.doubt 后接介词of：

There is no doubt of his competence for the task. 他的确有能力做好那项工作。

There is no doubt of his being guilty. 毫无疑问 他是有罪的。

She was a sweet little mortal to him; there was no doubt of that. 在他看来,她真是一个可爱的小人儿，这一点是勿庸置疑的。

He wore the satisfied smile of one who had no doubt of his success.他脸上满是一种稳操胜券的得意微笑。

I do not think there can be any doubt of your ability. 我信为您的能力是无可怀疑的。

I have no doubt of their being happy together. 我不怀疑他们在一起的快乐。

There is no doubt of his competence for the task. 他的确有能力做好那项工作。

We have no doubt of her ability. 我们相信她的能力。

5.doubt 后接介词as to：

There is no doubt as to his honesty. 至于他的诚实那是没有疑问的。

There is no doubt as to what he said. 有关他所说的话是不容置疑的。

There is no doubt as to who will be elected. 谁会当选,是毫无疑问的。

She had no doubt as to the correctness of her own estimate. 她对自己所作估计的正确性确信无疑。

They leave little doubt as to which culture they consider superior. 至于他们认为出众的文化他们甚少怀疑。

There can be no possible doubt as to their intention. 至于他们的意图,不可能有什么疑问。

I have no doubt as to his honesty. 对他的诚实,我毫无疑问。

There can be no doubt as to the importance of innovation in business. 商业上创新的重要性是毋庸置疑的。

There can not be any doubt as to who's responsible for the theft. 谁应对此次失窃负责是这无疑问的。

Doubt remains as to whether he is to work hard. 对于他是否准备好好工作,人们仍然心存疑虑。