Complex sentence: The Doctor and Martha pick up a distress signal from a man called'Professor Dinsdale' and rush to help, the TARDIS materialises and The Doctor leaves trying to find where the signal was coming from.
Split into simpler sentences: The Doctor and Martha pick up a distress signal from a man called'Professor Dinsdale' and rush to help. The TARDIS materialises and the Doctor leaves, trying to find where the signal was coming from.