Complex sentence: The Doctor explains to Rose that her actions have caused a paradox that normally the Time Lords would have prevented, but without them, the Reapers are sterilising the wound in time by consuming everyone within it.
Split into simpler sentences: The Doctor explains to Rose that her actions have caused a paradox that normally the Time Lords would have prevented. Without them, the Reapers are sterilising the wound in time by consuming everyone within it.