When the H1N1 virus____ at first in Mexico, no one had the least idea that it would spread so rapidly throughout the world.
The class __________ 80 students is hard to manage.
_________, he knows a lot about space and satellite.
The woman______ clothes in the supermarket was taken away by a policeman.
_______ studying English, he also studies Japanese.
It was the boy who_______ for the fight with his brother.