What are the rules for changing reported certainties in indirect speech?

The rules for changing reported certainties in indirect speech are as follows:

1. If the original statement is certain or affirmative, we use the reporting verb "said" or "told" followed by the reporting clause without any changes. For example:
- Direct speech: "I am going to the party tonight," she said.
- Indirect speech: She said that she was going to the party tonight.

2. If the original statement is uncertain or negative, we use the reporting verb "said" or "told" followed by the reporting clause with certain changes. These changes include:
- Changing the tense of the verb: Present simple becomes past simple, present continuous becomes past continuous, etc.
- Changing pronouns and possessive adjectives to match the subject of the reporting clause.
- Changing time and place expressions to reflect the time and place of the reporting clause.

For example:
- Direct speech: "I don't think I can make it to the meeting," he said.
- Indirect speech: He said that he didn't think he could make it to the meeting.

3. If the original statement expresses a future certainty, we use the reporting verb "said" or "told" followed by the reporting clause with certain changes. These changes include:
- Changing the future tense to the corresponding past tense.
- Changing time and place expressions to reflect the time and place of the reporting clause.

For example:
- Direct speech: "I will definitely finish the project by tomorrow," she said.
- Indirect speech: She said that she would definitely finish the project by the next day.

It is important to note that when changing reported certainties in indirect speech, we need to pay attention to the changes in verb tense, pronouns, possessive adjectives, and time/place expressions to accurately convey the original statement.