The process of producing electricity may also give out CO2, ______ you heat your house with electricity instead of charcoal.
Tom has gone to Shanghai,_____ is in the east of China.
__ he is young, he knows a lot.
I used to use English a lot and spent an hour each day _____ English books in the library.
___ the first day, at the meeting, I sat next ____ a girl named Diana.
It is in the big factory ______________my father works.