Direct speech vs Reported speech:
Direct speech: Bill said, 'I lived here last year.'
We use the exact words someone said with inverted commas.
Reported speech: Bill said (that) he had lived there the year before.
We introduce what someone said to our speech. Some changes are probably required since we are not with the same person, in the same day, in the same place...
Tense changes:
Generally speaking, when reporting someone's message, tenses tend to go back in time (one step to the past)
PRESENT SIMPLE -> PAST SIMPLE
PRESENT CONTINUOUS -> PAST CONTINUOUS
PRESENT PERFECT -> PAST PERFECT
PAST SIMPLE -> PAST PERFECT SIMPLE (it can also stay in past simple)
PAST CONTINUOUS -> PAST PERFECT CONTINUOUS
PAST PERFECT -> PAST PERFECT (no change is possible)
WILL -> WOULD
IS/ARE/AM GOING TO -> WAS/WERE GOING TO
CAN -> COULD
MAY -> MIGHT
MUST / HAVE TO -> HAD TO
SHOULD -> SHOULD
DS:
Mary said, 'I'm finishing in a while.'
RS:
Mary said (that) she was finishing in a while.
We do not change the tense with universal truths or when we are reporting something said at the same moment.
DS:
Mary said, 'The Earth is round.'
RS:
Mary said (that) the Earth is round.
Personal pronoun and adjective changes:
Subjects and objects have to change according to the circumstances and context.
DS:
Mary told Sam, 'I will love you forever.'
RS:
Mary told Sam (that) she would love him forever.
Place changes:
HERE -> THERE
DS:
Mary said, 'I will be here.'
RS:
Mary said (that) she would be there.
Time changes:
NOW / AT THE MOMENT -> THEN / AT THAT MOMENT
TODAY -> THAT DAY
YESTERDAY -> THE DAY BEFORE / THE PREVIOUS DAY
THE DAY BEFORE YESTERDAY -> TWO DAYS BEFORE
TOMORROW -> THE NEXT DAY / THE FOLLOWING DAY
THE DAY AFTER TOMORROW -> IN TWO DAYS TIME / TWO DAYS LATER
NEXT WEEK, MONTH, YEAR... -> THE FOLLOWING WEEK, MONTH, YEAR...
LAST WEEK, MONTH, YEAR... -> THE PREVIOUS WEEK, MONTH, YEAR...
[...] AGO -> [...] BEFORE
THIS (for time)
-> THAT (for time)
DS:
Mary said, 'I went to Morocco last year.'
RS:
Mary said (that) she had gone to Morocco the previous year.
We do not change the time when the action reported happens at the same moment.
Other changes:
THIS -> THAT / THE
THESE -> THOSE / THE
DS:
Mary said, 'I want this necklace.'
RS:
Mary said that she wanted that necklace.'