______ has already been pointed out, only by correcting mistakes, can you make progress.
This box __________ all the books you need, __________ an English-Chinese dictionary.
We'd better set off or it will be dark __________ we know it.
I ___________in the No.8 Middle School for three years, and I have been in this school for one and a half years.
Preparations are being made for the Olympic Games ______ in Brazil in 2016.
Mr Green has two daughters, both of____ are doctors.