Complex sentence: The Doctor realises she is the same woman as Oswin from the Dalek Asylum, and intrigued by a woman who has lived and died twice in different periods of history, he begins searching across time for another Clara.
Split into simpler sentences: The Doctor realises she is the same woman as Oswin from the Dalek Asylum. Intrigued by a woman who has lived and died twice in different eras, he begins searching across time for another Clara.