Mr. Black has been teaching English in a middle school _____ he came to China.
The most important thing_____we should pay attention to is the first thing _____I have said.
The World Wide Fund for Nature is an organization_____aim is to protect wildlife.
A container weighs more after air is put in,_____proves that air has weight.
I’ll take you to a shopping center nearby_____you may buy all_____you need.
Do you know the reason_____she didn’t attend her boyfriend’s birthday party yesterday?