把下列句子改为含有定语从句的句子
【小题1】The old man has two daughters，and both of them work as doctors.
The old man has two daughters，________________________________________.
【小题2】It is known to us that smoking is harmful to one’s health.
____________________________，smoking is harmful to one’s health.
【小题3】This is the factory.
A lot of students visited the factory yesterday.
This is the factory________________________________________________.
【小题4】The boy handed the handbag to the police.
He had found the handbag in the street.
The boy handed the handbag ________________________________________ to the police.
【小题5】The old man has two lovely dogs.
The old man lives next door.
The old man ____________________________ has two lovely dogs.
【小题6】This is the room which/that my grandmother used to live in.
This is the room _____________________________________________.