Question

"what are you building?"he asked

Answer 1

Answer:

he asked that what was I building.

Answer 2

Question :-- "what are you building?"he asked ..

This sentence was a statement.

When we change the narration of a simple statement, we do the following changes in the given sentence:

1. We connect reporting verb clause with quoted speech (direct speech) using 'that'

2. We change the tense of the quoted speech into the past tense.

3. We change the pronouns according to the subject and object.

Answer :-- He asked that what he was building ..