Example:
Statement:
1. He is good actor.
2. The world is round.
Noun Clauses:
A. I think That he is a good actor.
B. I think He is a good actor.
C. We know (That) the world is round.
Explanation: In (A): That he is a good actor is a noun clause. It is used as the object of the verb Think. The word That , when it introduces a noun clause has no meaning in itself. It simply the marks the beginning of the clause. Frequently it is omitted , as in (B), especially in speaking (If used in speaking, it is unstressed).
3. She doesn't understand spoken English
4. The world is round.
Noun Clauses:
D. That she doesn't understand spoken English is obvious.
E. It is obvious (That) she doesn't understand spoken English.
F. That the world is round is a fact.
G. It is a fact that the world is round
Explanation:
In (D): The noun clause (That she doesn't understand spoken English) is the subject of the sentence. The word That is not omitted when it introduces a noun clause used as the subject of a sentence, as in (D) and (F). More commonly the word it functions as the subject and the noun clause is placed at the end of the sentence, as in (E) and (G).