Final answer:
The direct question 'Why is she working so late?' is changed to the reported question 'He asked why she was working so late', reflecting the shift from present continuous to past continuous tense, and reordering from a question to a statement format.
Step-by-step explanation:
To convert the direct question 'Why is she working so late?' into a reported question, one must adjust both the verb tense and sentence structure to align with indirect speech norms. In this transformation, it's essential to remember that reported speech does not typically use question marks as the sentence becomes a statement. Here's how the sentence can be appropriately transformed:
He asked why she was working so late.
In this reported question, the direct question's present continuous tense ('is working') changes to past continuous ('was working') reflecting the backward shift typically applied in reported speech. Additionally, the word order changes from the direct question format to a statement format—a common feature of indirect questions.