Final answer:
To change the mode of narration, the sentence can be rewritten as: "The rajah asked his dear nephews what they had heard".
Step-by-step explanation:
The given statement is in direct speech mode and needs to be changed to indirect speech mode.
Indirect speech is speech which tells you what someone said, but does not use the person's actual words.
The mode of narration in the given sentence "the rajah said, 'my dear nephews, what is this that we hear?'", can be changed to indirect speech as follows: The rajah asked his dear nephews what it was that they had heard.
An example of Indirect speech: When using indirect or reported speech, the form changes. Usually indirect speech is introduced by the verb said, as in I said, Bill said, or they said.
Using the verb say in this tense, indicates that something was said in the past. In these cases, the main verb in the reported sentence is put in the past.