Sequence of Tenses Direct and Indirect Speech

If the main verb of the sentence is in the present, no change is made in the verb tense or modal in the object clause.

If the main verb of the sentence is in the past, the verb in the object clause is usually also in a past form.

He sais (that) he works hard.

He said (that) he worked hard.

He sais (that) he is working hard.

He said (that) he was working hard.

If the action of the object clause is simultaneous with that of the principal clause, the Past Indefinite or the Past Continuous is used in the object clause no matter which Past tense-aspect form is found in the principal clause.

He sais (that) he worked hard.

He said (that) he had worked hard.

He sais (that) he was working hard.

He said (that) he had been working hard.

He sais (that) she has already left.

He said (that) she had already left.

If the action of the object clause precedes that of the principal clause, the Past Perfect or the Past Perfect Continuous is used in the object clause no matter which Past tense-aspect form is found in the principal clause.

He sais (that) he will work hard.

He said (that) he would work hard.

He sais (that) he will have finished the work by September.

He said (that) he would have finished the work by September.

He sais (that) he will be working hard all day long.

He said (that) he would be working hard all day long.

If the action of the object clause follows that of the principal clause, the Future- in-the-Past or one of the other means of expressing future actions viewed from the past is used in the object clause no matter which Past tense-aspect form is found in the principal clause.

He sais (that) he is going to work hard.

He said (that) he was going to work hard.

He sais (that) he can work hard.

He said (that) he could work hard.

He sais (that) he may work hard.

He said (that) he might work hard.

He sais (that) he has to work hard.

He said (that) he had to work hard.

He sais (that) he must work hard.

He said (that) he had to work hard.

He sais (that) he should work hard.

He said (that) he should work hard.

He sais (that) he ought to work hard.

He said (that) he ought to work hard.

The rules of sequence of tenses cannot be observed with certain modal verbs which have only one form. (must, should, ought and need)