example change direct speech into indirect speech

Direct speech		Indirect speech
Present simple She said, "It's cold."	›	Past simple She said it was cold.
Present continuous She said, "I'm teaching English online."	›	Past continuous She said she was teaching English online.
Present perfect simple She said, "I've been on the web since 1999."	›	Past perfect simple She said she had been on the web since 1999.
Present perfect continuous She said, "I've been teaching English for seven years."	›	Past perfect continuous She said she had been teaching English for seven years.
Past simple She said, "I taught online yesterday."	›	Past perfect She said she had taught online yesterday.
Past continuous She said, "I was teaching earlier."	›	Past perfect continuous She said she had been teaching earlier.
Past perfect She said, "The lesson had already started when he arrived."	›	Past perfect NO CHANGE - She said the lesson had already started when he arrived.
Past perfect continuous She said, "I'd already been teaching for five minutes."	›	Past perfect continuous NO CHANGE - She said she'd already been teaching for five minutes.

Modal verb forms also sometimes change:

Direct speech		Indirect speech
will She said, "I'll teach English online tomorrow."	›	would She said she would teach English online tomorrow.
can She said, "I can teach English online."	›	could She said she could teach English online.
must She said, "I must have a computer to teach English online."	›	had to She said she had to have a computer to teach English online.
shall She said, "What shall we learn today?"	›	should She asked what we should learn today.
may She said, "May I open a new browser?"	›	might She asked if she might open a new browser.

!Note - There is no change to; could, would, should, might and ought to

sumber :

http://www.learnenglish.de/grammar/reportedspeech.htm