Question

I don't know when he returns.(simple sentence with noun clause)

Answer 1

when he returns (is your noun clause)

Answer 2

▪SIMPLE SENTENCE

=》I don't know the time of his return.

▪EXPLANATION

=》When changing sentences from one state to another, always read and try to avoid any confusion. Some sentences may be hard to change but remember that the tense may change to ensure the sentence makes meaning. Other words are also eliminated to retain the purpose of the initial sentence despite the structure of the new one.

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