The subordinate clause is "you must start researching now"
Batman is a hero and he saves the city from a lot of criminals.
There was a meteor shower, yet the crew did not know how to avoid the meteors.
Gillian did not like to read and she was not very good at it.
(5) during the industrial revoltion,too,homeless people provided much needed labor in the nation's factories
The mood (or tone) of the prologue is considered as sombre, dark, macabre... since from the start we're being told that this story is going to be a story of love, death and loss.