Sequence of Tenses and Exceptions

When the verb in the main clause is in the past tense, the rule of shifting the verb in a subordinate clause such as a that clause into the past is called the sequence of tenses. This rule frequently appears in reported speech and explanatory writing.

Basic Rules

When the main clause is in the past tense (said / thought / told / believed, etc.), shift the verb in the subordinate clause as follows:
- Present tense → past tense “He says he is busy. → He said he was busy.”
- Past tense → past perfect “He says he was sick. → He said he had been sick.”
- Present perfect → past perfect “He says he has finished. → He said he had finished.”
- will → would “He says he will come. → He said he would come.”
- can → could / may → might / must → had to (in some cases)

Exceptions to the sequence of tenses:
① Unchanging truths / universal facts: “She said that the Earth goes around the sun.” ← It is acceptable not to shift the tense
② Facts that continue to be true: “He told me that he lives in Tokyo.” ← lives is acceptable if he still lives there
③ Historical facts: “He said that Columbus discovered America in 1492.” ← remains in the past tense
④ Subjunctive mood: subjunctive verbs are not affected by the sequence of tenses “He said if he were rich, he would buy a yacht.”

Points to Note

① Sequence of tenses for auxiliary verbs:
- can → could
- will → would
- may → might
- shall → should
- must → had to (for obligation) / remains must (for inference, it is sometimes unchanged)
② Adverb replacement: In changing direct speech to reported speech, adverbs also change
- now → then
- today → that day
- tomorrow → the next day / the following day
- yesterday → the day before / the previous day
- this → that
- here → there
③ The rule that truths remain in the present tense is important in academic and scientific writing. “Galileo said that the Earth moves. (moves)” ← There is no need to change it to moved.
④ Exception involving the subjunctive: The tense does not change in the subjunctive. Even in reported speech, “If I were you, ...” becomes “He said that if he were me, he would ...,” with were unchanged.

Practice

1. Change the following direct speech into reported speech: He said, "I will come tomorrow."
2. Determine the tense issue in the following sentence: My teacher told us that water boils at 100℃.
3. Change the following sentence into reported speech: She said, "I have finished my homework."