Sequence of tenses

The sequence of tenses is a dependence of the tense form of the predicate in a subordinate clause on the tense form of the predicate in its principal clause.

The rules mainly concern object clauses depending on principal clauses with the predicate verb in one of the past tenses, though it holds true also for some other subordinate clauses (such as subject, predicative and appositive ones).
The rules are as follows:

a present (or future) tense in the principal clause may be followed by any tense in the subordinate object clause:

2) a past tense in the principal clause is followed by a past tense in the subordinate object clause.

The rules of the sequence of tenses concern subordinate clauses dependent not only on the predicate of the principal clause but also on any part expressed by a verb or verbal:
I received from her a letter saying that she was passing through Paris and would like to have a chat with me.
She smiled again, sure that I should come up.
She turned her head slightly, well aware that he was watching her.

In complex sentences containing more than two subordinate clauses the choice of the tense form for each of them depends on the tense form of the clause to which it is subordinated:
I guess you told him where they had come from and why they were hiding.
As far as I can see he did not realize that very soon all would be over.
Besides the complex sentences described above the rules of the se­quence of tenses are also found in all types of clauses and simple sentences reproducing inner speech (conventional direct speech).

The rules of the sequence of tenses are not observed in the following cases
1) when the subordinate clause describes the so-called general truth, or something which the speaker thinks to be one.
Up to then Roy never realized that our Solar system is but a tiny speck in the infinite Universe.
The other day I read in a book that everything alive consists mostly of water.
She was very young and - and ignorant of what life really is.

2) when the subordinate clause describes actions referring to the actual present, future, or past time, which usually occurs in dialogues or in newspaper, radio, or TV reports.
Margaret, I was saying to you - and I beg you to listen to me – that as far as I have known Mrs. Erlynne, she has conducted herself well.
“Before the flier crashed,” the operator said ten minutes later, “he gave me information. He told me there are still a few men alive in these mountains.”
I did not know he will be here tomorrow.

3) when the predicate verb of the subordinate clause is one of the modal verbs having no past tense forms.
She said I must come at once.
I thought you should come too.

REPORTED SPEECH
We use the indirect (reported speech) when we are telling someone what other person says or said.
The tense of the reporting verb ( say, tell, ask...) often affects the tense of the reported statement:
e.g. He says: “The campaign is a great success”. D
He says (that) the campaign is a great success. I
e.g. He said: “The campaign is a great success”. D
He said (that) the campaign was a great success. I

The change of tenses
When the reporting verb is in a past tense, the following changes may occur in the reported sentence:
Present simple →Past Simple
Past Simple →Past Perfect
Present Perfect →Past Perfect
Present Continuous →Past Continuous
Present Perfect Continuous→Past Perfect Continuous
will →would
can →could
must →had to

People, places, times and things
People I → he/she
you → me
my → his/her
your → mine
Place here → there
Times now → then, at the time
today → that day, on Monday
yesterday → the day before, the previous day
tomorrow → the next day, the following day
this afternoon → that afternoon
last week → the week before, the previous week
next week → the week after, the following week
a few days ago → a few days before
Things this project → that project

Modal verbs
Will
Can
May
Must
Could have done
Might have done
Should have done
Need’t have done
Must or had to
Would
Could
Might
Do not change

CHANGES OF ADVERBIALS, DEMONSTRATIVE PRONOUNS AND SOME OTHER WORDS
KARNEVSKAYA, p. 206

Time and place changes
Here
This
These
Now
Today
Yesterday
A year ago
Last night
Tonight
there
that
those
that day
then / at that moment
the day before / the previous day
a year before
the previous night
that night
Adverb changes depend on the context. It is not always necessary to make these changes, especially in spoken Indirect Speech.

Exception!
We do not change tense if the information is still true.
e.g. He said that the sky is blue.
He said that the sun rises in the east.
He said there is always a period of uncertainty after a merger.

Say or Tell
We say something and we tell somebody
e.g. John said he was satisfied with the project.
John told me he was satisfied with the project.
Never use TO between tell and object
Other Reporting Verbs
Verb + -ing admit, deny, mention, propose, suggest…
Verb + to infinitive agree, ask, demand, decide, offer…
Verb + that clause admit, claim, promise, confirm…
e.g. He said: “I didn’t do that.”
He denied doing that.

Reporting Questions
Mind the word order!
WH-questions:
reporting verb + WH-word + subject + main verb
e.g. Where is it?”
He asked me where it was.
When will the goods arrive?”
They asked me when the goods would arrive.
What time does the train leave?
They wanted to know when the train left.

Reporting Questions
Mind the word order!
2. Yes/ No Questions
reporting verb + IF/ WHETHER + subject
+ main
verb
e.g. Do you speak French?
She asked me if I spoke French.
Are you going to pay in cash?
He asked me whether I was going to pay in cash.

Reporting Commands and Requests
Reporting verb+ subject + to/ not to + infinitive
e.g. Take us to the airport.
She told the driver to take us to the airport.
e.g. Please don’t wait for me, I’ll come along later.” He asked us not to wait.

Reporting Statements:
1 'I have something to show you,' I said to her.
2 'Nothing grows in my garden. It never gets any sun,' she said.
3 'I'm going away tomorrow, mother,' he said.
4 'I've been in London for a month but so far I haven't had time to visit the Tower,' said Rupert.
5 'It isn't so foggy today as it was yesterday,' I remarked.
6 'We have a lift but very often it doesn't work,' they said.
7 'I've no idea what the time is but I'll dial 8081 and find out,' said his daughter.
8 He said, 'My wife has just been made a judge.'
9 'I'll come with you as soon as I am ready,' she replied.
10 'If you let the iron get too hot you will scorch your clothes,' I warned her.

Reporting questions
1 'Why are you looking through the keyhole?' I said.
2 'Who put salt in my coffee?' he asked.
3 'Which of you knows how to make Irish stew?' said the chief cook
4 'Why did you travel first class?' I asked him.
5 'How can I run in high-heeled shoes?' she enquired.
6 'Who owns this revolver?' said the detective.
7 'Have you done this sort of work before?' said his new employer
8 'Do you see what I see, Mary?' said the young man.
9 'Are you leaving today or tomorrow morning?' said his secretary.
10 'Will you go on strike when the others do?' the shop steward asked him.