Tom has been in the factory _________he left school.
— What does Mary do? — Her job ________ helping old people who live alone.
It has been announced by our provincial government that another two medical teams will be sent to _______ the injured people in the severe earthquake.
The invention of steam engine greatly sped up the industrial revolution, which ________ a lot to the take-off of the world.
__________I see him, he looks sad.
A quarrel _________, which made him __________ his family.