Questions (3): formation of indirect questions
As shown in questions (1): direct or indirect above, there is an important difference between the way in which we report questions and the way in which we actually ask them. In indirect, or reported, questions, we do not need question marks or speech marks. When we report questions in speech, we do not raise our voices at the end of the sentence, as we normally do to ask direct questions.
There is also a change in tense, as is normal in reported speech (q.v.). In the most common examples, indirect questions are introduced by verbs of utterance in the past tense, e.g. 'he said'. After these, a direct question in the present tense is reported with the past tense. Where the direct question was in the past tense ("What has happened to you?"), the reported version uses the past perfect: "She asked what had happened to him."
The indirect equivalent of a direct yes/no question usually uses the conjunction 'whether' or 'if' following the verb of utterance. The direct question "Would you like a cup of tea?" can, for example, be reported as "She asked whether he would like a cup of tea", or "She asked him if he would like a cup of tea." In academic English, whether is to be preferred to if for reporting yes/no questions. (This can be very clear if whether... is followed by ...or not. If may be better for more open-ended questions.