We can use clauses with that:
• after verbs of thinking:
I hope that you will enjoy your holiday.
She didn’t really think that it would happen.
I knew that I had seen her somewhere before.
• after verbs of saying:
They admitted that they had made a mistake.
She argued that they should invest more in the business.
The children complained that they had nothing to do.
Note: tell and some other verbs of saying must always have a direct object (see clauses, sentences and phrases):
We tried to tell them that they should stop what they were doing.
The police informed everybody that the danger was over.
• as postmodifiers after nouns to do with thinking or saying:
He made a promise that he would do all he could to help.
I had a funny feeling that something was wrong.
• after some nouns to say more about the noun:
She pointed out the danger that they might be left behind.
There was a chance that we would succeed
Note: We often use a that clause to define one of these nouns after the verb be :
The danger is that we will be left behind.
The fact is that it is getting very late.
• after some adjectives which describe feelings to give a reason for our feelings:
I am sorry that you can’t come.
Everybody was pleased that the danger was past.
It is lucky that you were able to drive us home.
NOTE: We can always use a clause without the word that:
They admitted [that] they had made a mistake.
The police informed everybody [that] the danger was over.
I am sorry [that] you can’t come.
There was chance [that] we would succeed.